Unix Domain Socket auto discovery (#833)

This PR adds end-to-end Unix domain socket (UDS) support, allowing zen CLI to discover and connect to UDS-only servers automatically.

- **`unix://` URI scheme in zen CLI**: The `-u` / `--hosturl` option now accepts `unix:///path/to/socket` to connect to a zenserver via a Unix domain socket instead of TCP.
- **Per-instance shared memory for extended server info**: Each zenserver instance now publishes a small shared memory section (keyed by SessionId) containing per-instance data that doesn't fit in the fixed-size ZenServerEntry -- starting with the UDS socket path. This is a 4KB pagefile-backed section on Windows (`Global\ZenInstance_{sessionid}`) and a POSIX shared memory object on Linux/Mac (`/UnrealEngineZen_{sessionid}`).
- **Client-side auto-discovery of UDS servers**: `zen info`, `zen status`, etc. now automatically discover and prefer UDS connections when a server publishes a socket path. Servers running with `--no-network` (UDS-only) are no longer invisible to the CLI.
- **`kNoNetwork` flag in ZenServerEntry**: Servers started with `--no-network` advertise this in their shared state entry. Clients skip TCP fallback for these servers, and display commands (`ps`, `status`, `top`) show `-` instead of a port number to indicate TCP is not available.

3 files changed, 11 insertions, 6 deletions

diff --git a/src/zenhttp/include/zenhttp/httpclient.h b/src/zenhttp/include/zenhttp/httpclient.h
index 03c98af7e..e95d78772 100644
--- a/src/zenhttp/include/zenhttp/httpclient.h
+++ b/src/zenhttp/include/zenhttp/httpclient.h
@@ -10,6 +10,7 @@
 #include <zencore/uid.h>
 #include <zenhttp/httpcommon.h>
 
+#include <filesystem>
 #include <functional>
 #include <optional>
 #include <unordered_map>
@@ -91,7 +92,7 @@ struct HttpClientSettings
 
 	/// Unix domain socket path. When non-empty, the client connects via this
 	/// socket instead of TCP. BaseUri is still used for the Host header and URL.
-	std::string UnixSocketPath;
+	std::filesystem::path UnixSocketPath;
 
 	/// Disable HTTP keep-alive by closing the connection after each request.
 	/// Useful for testing per-connection overhead.
@@ -174,11 +175,14 @@ class HttpClientBase;
 class HttpClient
 {
 public:
-	HttpClient(std::string_view			 BaseUri,
-			   const HttpClientSettings& Connectionsettings	  = {},
-			   std::function<bool()>&&	 CheckIfAbortFunction = {});
+	explicit HttpClient(std::string_view		  BaseUri,
+						const HttpClientSettings& Connectionsettings   = {},
+						std::function<bool()>&&	  CheckIfAbortFunction = {});
 	~HttpClient();
 
+	HttpClient(const HttpClient&) = delete;
+	HttpClient& operator=(const HttpClient&) = delete;
+
 	struct ErrorContext
 	{
 		HttpClientErrorCode ErrorCode;
diff --git a/src/zenhttp/include/zenhttp/httpserver.h b/src/zenhttp/include/zenhttp/httpserver.h
index 627e7921f..77feb6568 100644
--- a/src/zenhttp/include/zenhttp/httpserver.h
+++ b/src/zenhttp/include/zenhttp/httpserver.h
@@ -15,6 +15,7 @@
 
 #include <zentelemetry/stats.h>
 
+#include <filesystem>
 #include <functional>
 #include <gsl/gsl-lite.hpp>
 #include <list>
@@ -329,7 +330,7 @@ struct HttpServerConfig
 	std::vector<HttpServerPluginConfig> PluginConfigs;
 	bool								ForceLoopback = false;
 	unsigned int						ThreadCount	  = 0;
-	std::string							UnixSocketPath;		// Unix domain socket path (empty = disabled, non-Windows only)
+	std::filesystem::path				UnixSocketPath;		// Unix domain socket path (empty = disabled)
 	bool								NoNetwork = false;	// Disable TCP/HTTPS listeners; only accept connections via UnixSocketPath
 	int									HttpsPort = 0;		// HTTPS listen port (0 = disabled, ASIO backend)
 	std::string							CertFile;			// PEM certificate chain file path
diff --git a/src/zenhttp/include/zenhttp/httpwsclient.h b/src/zenhttp/include/zenhttp/httpwsclient.h
index 34d338b1d..2ca9b7ab1 100644
--- a/src/zenhttp/include/zenhttp/httpwsclient.h
+++ b/src/zenhttp/include/zenhttp/httpwsclient.h
@@ -46,7 +46,7 @@ struct HttpWsClientSettings
 
 	/// Unix domain socket path. When non-empty, connects via this socket
 	/// instead of TCP. The URL host is still used for the Host header.
-	std::string UnixSocketPath;
+	std::filesystem::path UnixSocketPath;
 };
 
 /**