Dashboard refresh (logs, storage, network, object store, docs) (#835)

## Summary

This PR adds a session management service, several new dashboard pages, and a number of infrastructure improvements.

### Sessions Service
- `SessionsServiceClient` in `zenutil` announces sessions to a remote zenserver with a 15s heartbeat (POST/PUT/DELETE lifecycle)
- Storage server registers itself with its own local sessions service on startup
- Session mode attribute coupled to server mode (Compute, Proxy, Hub, etc.)
- Ended sessions tracked with `ended_at` timestamp; status filtering (Active/Ended/All)
- `--sessions-url` config option for remote session announcement
- In-process log sink (`InProcSessionLogSink`) forwards server log output to the server's own session, visible in the dashboard

### Session Log Viewer
- POST/GET endpoints for session logs (`/sessions/{id}/log`) supporting raw text and structured JSON/CbObject with batch `entries` array
- In-memory log storage per session (capped at 10k entries) with cursor-based pagination for efficient incremental fetching
- Log panel in the sessions dashboard with incremental DOM updates, auto-scroll (Follow toggle), newest-first toggle, text filter, and log-level coloring
- Auto-selects the server's own session on page load

### TCP Log Streaming
- `LogStreamListener` and `TcpLogStreamSink` for log delivery over TCP
- Sequence numbers on each message with drop detection and synthetic "dropped" notice on gaps
- Gathered buffer writes to reduce syscall overhead when flushing batches
- Tests covering basic delivery, multi-line splitting, drop detection, and sequencing

### New Dashboard Pages
- **Sessions**: master-detail layout with selectable rows, metadata panel, live WebSocket updates, paging, abbreviated date formatting, and "this" pill for the local session
- **Object Store**: summary stats tiles and bucket table with click-to-expand inline object listing (`GET /obj/`)
- **Storage**: per-volume disk usage breakdown (`GET /admin/storage`), Garbage Collection status section (next-run countdown, last-run stats), and GC History table with paginated rows and expandable detail panels
- **Network**: overview tiles, per-service request table, proxy connections, and live WebSocket updates; distinct client IPs and session counts via HyperLogLog

### Documentation Page
- In-dashboard Docs page with sidebar navigation, markdown rendering (via `marked`), Mermaid diagram support (theme-aware), collapsible sections, text filtering with highlighting, and cross-document linking
- New user-facing docs: `overview.md` (with architecture and per-mode diagrams), `sessions.md`, `cache.md`, `projects.md`; updated `compute.md`
- Dev docs moved to `docs/dev/`

### Infrastructure & Bug Fixes
- **Deflate compression** for the embedded frontend zip (~3.4MB → ~950KB); zlib inflate support added to `ZipFs` with cached decompressed buffers
- **Local IP addresses**: `GetLocalIpAddresses()` (Windows via `GetAdaptersAddresses`, Linux/Mac via `getifaddrs`); surfaced in `/status/status`, `/health/info`, and the dashboard banner
- **Dashboard nav**: unified into `zen-nav` web component with `MutationObserver` for dynamically added links, CSS `::part()` to merge banner/nav border radii, and prefix-based active link detection
- Stats broadcast refactored from manual JSON string concatenation to `CbObjectWriter`; `CbObject`-to-JS conversion improved for `TimeSpan`, `DateTime`, and large integers
- Stats WebSocket boilerplate consolidated into `ZenPage.connect_stats_ws()`

1 files changed, 193 insertions, 37 deletions

diff --git a/src/zenutil/splitconsole/logstreamlistener.cpp b/src/zenutil/splitconsole/logstreamlistener.cpp
index 9f1d1a02c..04718b543 100644
--- a/src/zenutil/splitconsole/logstreamlistener.cpp
+++ b/src/zenutil/splitconsole/logstreamlistener.cpp
@@ -2,6 +2,7 @@
 
 #include <zenutil/splitconsole/logstreamlistener.h>
 
+#include <zenbase/refcount.h>
 #include <zencore/compactbinary.h>
 #include <zencore/fmtutils.h>
 #include <zencore/logging.h>
@@ -11,7 +12,6 @@ ZEN_THIRD_PARTY_INCLUDES_START
 #include <asio.hpp>
 ZEN_THIRD_PARTY_INCLUDES_END
 
-#include <atomic>
 #include <vector>
 
 namespace zen {
@@ -19,21 +19,17 @@ namespace zen {
 //////////////////////////////////////////////////////////////////////////
 // LogStreamSession — reads CbObject-framed messages from a single TCP connection
 
-class LogStreamSession : public std::enable_shared_from_this<LogStreamSession>
+class LogStreamSession : public RefCounted
 {
 public:
-	LogStreamSession(asio::ip::tcp::socket Socket, std::atomic<LogStreamHandler*>& Handler)
-	: m_Socket(std::move(Socket))
-	, m_Handler(Handler)
-	{
-	}
+	LogStreamSession(asio::ip::tcp::socket Socket, LogStreamTarget& Target) : m_Socket(std::move(Socket)), m_Target(Target) {}
 
 	void Start() { DoRead(); }
 
 private:
 	void DoRead()
 	{
-		auto Self = shared_from_this();
+		Ref<LogStreamSession> Self(this);
 		m_Socket.async_read_some(asio::buffer(m_ReadBuf.data() + m_BufferUsed, m_ReadBuf.size() - m_BufferUsed),
 								 [Self](const asio::error_code& Ec, std::size_t BytesRead) {
 									 if (Ec)
@@ -71,8 +67,17 @@ private:
 			std::string_view Text	= Obj["text"].AsString();
 			std::string_view Source = Obj["source"].AsString();
 
+			// Check sequence number for gaps (dropped messages)
+			uint64_t Seq = Obj["seq"].AsUInt64();
+			if (Seq > m_NextExpectedSeq)
+			{
+				uint64_t Dropped = Seq - m_NextExpectedSeq;
+				m_Target.AppendLogLine(fmt::format("[{}] *** {} log message(s) dropped ***", Source.empty() ? "log" : Source, Dropped));
+			}
+			m_NextExpectedSeq = Seq + 1;
+
 			// Split multi-line messages into individual AppendLogLine calls so that
-			// each line gets its own row in the SplitConsole ring buffer.
+			// each line gets its own row in the target's log output.
 			while (!Text.empty())
 			{
 				std::string_view Line = Text;
@@ -98,17 +103,13 @@ private:
 					continue;
 				}
 
-				LogStreamHandler* Handler = m_Handler.load(std::memory_order_acquire);
-				if (Handler)
+				if (!Source.empty())
 				{
-					if (!Source.empty())
-					{
-						Handler->AppendLogLine(fmt::format("[{}] {}", Source, Line));
-					}
-					else
-					{
-						Handler->AppendLogLine(std::string(Line));
-					}
+					m_Target.AppendLogLine(fmt::format("[{}] {}", Source, Line));
+				}
+				else
+				{
+					m_Target.AppendLogLine(Line);
 				}
 			}
 
@@ -128,10 +129,11 @@ private:
 		}
 	}
 
-	asio::ip::tcp::socket			m_Socket;
-	std::atomic<LogStreamHandler*>& m_Handler;
-	std::array<uint8_t, 65536>		m_ReadBuf{};
-	std::size_t						m_BufferUsed = 0;
+	asio::ip::tcp::socket	   m_Socket;
+	LogStreamTarget&		   m_Target;
+	std::array<uint8_t, 65536> m_ReadBuf{};
+	std::size_t				   m_BufferUsed		 = 0;
+	uint64_t				   m_NextExpectedSeq = 0;
 };
 
 //////////////////////////////////////////////////////////////////////////
@@ -140,7 +142,10 @@ private:
 struct LogStreamListener::Impl
 {
 	// Owned io_context mode — creates and runs its own thread
-	explicit Impl(uint16_t Port) : m_OwnedIoContext(std::make_unique<asio::io_context>()), m_Acceptor(*m_OwnedIoContext)
+	Impl(LogStreamTarget& Target, uint16_t Port)
+	: m_Target(Target)
+	, m_OwnedIoContext(std::make_unique<asio::io_context>())
+	, m_Acceptor(*m_OwnedIoContext)
 	{
 		SetupAcceptor(Port);
 		m_IoThread = std::thread([this]() {
@@ -150,7 +155,10 @@ struct LogStreamListener::Impl
 	}
 
 	// External io_context mode — caller drives the io_context
-	Impl(asio::io_context& IoContext, uint16_t Port) : m_Acceptor(IoContext) { SetupAcceptor(Port); }
+	Impl(LogStreamTarget& Target, asio::io_context& IoContext, uint16_t Port) : m_Target(Target), m_Acceptor(IoContext)
+	{
+		SetupAcceptor(Port);
+	}
 
 	~Impl() { Shutdown(); }
 
@@ -177,11 +185,12 @@ struct LogStreamListener::Impl
 
 	uint16_t GetPort() const { return m_Port; }
 
-	void SetHandler(LogStreamHandler* Handler) { m_Handler.store(Handler, std::memory_order_release); }
-
 private:
 	void SetupAcceptor(uint16_t Port)
 	{
+		auto& IoCtx = m_OwnedIoContext ? *m_OwnedIoContext : m_Acceptor.get_executor().context();
+		ZEN_UNUSED(IoCtx);
+
 		// Try dual-stack IPv6 first (accepts both IPv4 and IPv6), fall back to IPv4-only
 		asio::error_code Ec;
 		m_Acceptor.open(asio::ip::tcp::v6(), Ec);
@@ -218,7 +227,7 @@ private:
 				return;	 // acceptor closed
 			}
 
-			auto Session = std::make_shared<LogStreamSession>(std::move(Socket), m_Handler);
+			Ref<LogStreamSession> Session(new LogStreamSession(std::move(Socket), m_Target));
 			Session->Start();
 
 			if (!m_Stopped.load())
@@ -228,7 +237,7 @@ private:
 		});
 	}
 
-	std::atomic<LogStreamHandler*>	  m_Handler{nullptr};
+	LogStreamTarget&				  m_Target;
 	std::unique_ptr<asio::io_context> m_OwnedIoContext;	 // null when using external io_context
 	asio::ip::tcp::acceptor			  m_Acceptor;
 	std::thread						  m_IoThread;
@@ -239,22 +248,17 @@ private:
 //////////////////////////////////////////////////////////////////////////
 // LogStreamListener
 
-LogStreamListener::LogStreamListener(uint16_t Port) : m_Impl(std::make_unique<Impl>(Port))
+LogStreamListener::LogStreamListener(LogStreamTarget& Target, uint16_t Port) : m_Impl(std::make_unique<Impl>(Target, Port))
 {
 }
 
-LogStreamListener::LogStreamListener(asio::io_context& IoContext, uint16_t Port) : m_Impl(std::make_unique<Impl>(IoContext, Port))
+LogStreamListener::LogStreamListener(LogStreamTarget& Target, asio::io_context& IoContext, uint16_t Port)
+: m_Impl(std::make_unique<Impl>(Target, IoContext, Port))
 {
 }
 
 LogStreamListener::~LogStreamListener() = default;
 
-void
-LogStreamListener::SetHandler(LogStreamHandler* Handler)
-{
-	m_Impl->SetHandler(Handler);
-}
-
 uint16_t
 LogStreamListener::GetPort() const
 {
@@ -268,3 +272,155 @@ LogStreamListener::Shutdown()
 }
 
 }  // namespace zen
+
+#if ZEN_WITH_TESTS
+
+#	include <zencore/testing.h>
+#	include <zenutil/splitconsole/tcplogstreamsink.h>
+
+namespace zen {
+
+void
+logstreamlistener_forcelink()
+{
+}
+
+namespace {
+
+	class CollectingTarget : public LogStreamTarget
+	{
+	public:
+		void AppendLogLine(std::string_view Text) override
+		{
+			std::lock_guard<std::mutex> Lock(m_Mutex);
+			m_Lines.emplace_back(Text);
+			m_Cv.notify_all();
+		}
+
+		std::vector<std::string> WaitForLines(size_t Count, std::chrono::milliseconds Timeout = std::chrono::milliseconds(5000))
+		{
+			std::unique_lock<std::mutex> Lock(m_Mutex);
+			m_Cv.wait_for(Lock, Timeout, [&]() { return m_Lines.size() >= Count; });
+			return m_Lines;
+		}
+
+	private:
+		std::mutex				 m_Mutex;
+		std::condition_variable	 m_Cv;
+		std::vector<std::string> m_Lines;
+	};
+
+	logging::LogMessage MakeLogMessage(std::string_view Text, logging::LogLevel Level = logging::Info)
+	{
+		static logging::LogPoint Point{{}, Level, {}};
+		Point.Level = Level;
+		return logging::LogMessage(Point, "test", Text);
+	}
+
+}  // namespace
+
+TEST_SUITE_BEGIN("util.logstreamlistener");
+
+TEST_CASE("BasicMessageDelivery")
+{
+	CollectingTarget  Target;
+	LogStreamListener Listener(Target);
+
+	{
+		TcpLogStreamSink Sink("127.0.0.1", Listener.GetPort(), "TestSource", 64);
+		Sink.Log(MakeLogMessage("hello world"));
+		Sink.Log(MakeLogMessage("second line"));
+	}
+
+	auto Lines = Target.WaitForLines(2);
+	REQUIRE(Lines.size() == 2);
+	CHECK(Lines[0] == "[TestSource] hello world");
+	CHECK(Lines[1] == "[TestSource] second line");
+}
+
+TEST_CASE("MultiLineMessageSplit")
+{
+	CollectingTarget  Target;
+	LogStreamListener Listener(Target);
+
+	{
+		TcpLogStreamSink Sink("127.0.0.1", Listener.GetPort(), "src", 64);
+		Sink.Log(MakeLogMessage("line1\nline2\nline3"));
+	}
+
+	auto Lines = Target.WaitForLines(3);
+	REQUIRE(Lines.size() == 3);
+	CHECK(Lines[0] == "[src] line1");
+	CHECK(Lines[1] == "[src] line2");
+	CHECK(Lines[2] == "[src] line3");
+}
+
+TEST_CASE("DroppedMessageDetection")
+{
+	// Test sequence-gap detection deterministically by sending raw CbObjects
+	// with an explicit gap in sequence numbers, bypassing TcpLogStreamSink.
+	CollectingTarget  Target;
+	LogStreamListener Listener(Target);
+
+	{
+		asio::io_context	  IoContext;
+		asio::ip::tcp::socket Socket(IoContext);
+		Socket.connect(asio::ip::tcp::endpoint(asio::ip::make_address("127.0.0.1"), Listener.GetPort()));
+
+		// Send seq=0, then seq=5 — the listener should detect a gap of 4
+		for (uint64_t Seq : {uint64_t(0), uint64_t(5)})
+		{
+			CbObjectWriter Writer;
+			Writer.AddString("text", fmt::format("msg{}", Seq));
+			Writer.AddString("source", "src");
+			Writer.AddInteger("seq", Seq);
+			CbObject   Obj	= Writer.Save();
+			MemoryView View = Obj.GetView();
+
+			asio::write(Socket, asio::buffer(View.GetData(), View.GetSize()));
+		}
+	}
+
+	// Expect: msg0, drop notice, msg5
+	auto Lines = Target.WaitForLines(3);
+	REQUIRE(Lines.size() >= 3);
+	CHECK(Lines[0] == "[src] msg0");
+	CHECK(Lines[1].find("4 log message(s) dropped") != std::string::npos);
+	CHECK(Lines[2] == "[src] msg5");
+}
+
+TEST_CASE("SequenceNumbersAreContiguous")
+{
+	CollectingTarget  Target;
+	LogStreamListener Listener(Target);
+
+	constexpr int NumMessages = 5;
+	{
+		TcpLogStreamSink Sink("127.0.0.1", Listener.GetPort(), "seq", 64);
+		for (int i = 0; i < NumMessages; i++)
+		{
+			Sink.Log(MakeLogMessage(fmt::format("msg{}", i)));
+		}
+	}
+
+	auto Lines = Target.WaitForLines(NumMessages);
+	REQUIRE(Lines.size() == NumMessages);
+
+	// No "dropped" notices should appear when nothing is dropped
+	for (auto& Line : Lines)
+	{
+		CHECK(Line.find("dropped") == std::string::npos);
+	}
+
+	// Verify ordering
+	for (int i = 0; i < NumMessages; i++)
+	{
+		CHECK(Lines[i] == fmt::format("[seq] msg{}", i));
+	}
+}
+
+TEST_SUITE_END();
+
+}  // namespace zen
+
+#endif