zen trace analysis support (#945)

Integrates the **tourist** trace analysis library and builds a full `zen trace` command suite for working with Unreal Engine `.utrace` files.

### Trace analysis library (`thirdparty/tourist/`)
- Adds the tourist library as a third-party dependency with three modules: **foundation** (platform primitives, memory, scheduling), **trace** (UE Trace protocol decoding), and **analysis** (event dispatching and analyzer framework).
- Cross-platform support for Windows, Linux, and macOS.

### `zen trace` CLI commands (`src/zen/cmds/`, `src/zen/trace/`)
- **`zen trace analyze`** — Summarize a `.utrace` file: session metadata, thread inventory, command line + build configuration, CPU profiling scopes, timing, event rates, log messages, and (with symbols) memory allocation metrics including live-allocs dumps, callstack-keyed aggregation, and allocation churn. Optional HTML output for memory reports.
- **`zen trace inspect`** — Dump the event schema (declared types, fields, sizes) from a trace file.
- **`zen trace trim`** — Extract a time-window from a trace into a new `.utrace` file.
- **`zen trace serve`** — Launch a local HTTP server hosting an interactive trace viewer; opens in the default browser.

### Symbolication (`src/zen/trace/symbol_resolver.*`, `thirdparty/raw_pdb/`)
- Pluggable resolver with multiple backends: `pdb` (in-tree raw_pdb), `dbghelp` (Windows), `llvm-symbolizer` (all platforms), `atos` (macOS). An `auto` backend picks the best available tool per platform.
- Microsoft Symbol Server support: downloads PDBs on demand using a redirect-aware HTTP client.
- Local PDB cache keyed by image GUID preserves symbols across binary recompilation.
- Callstack trimming heuristic strips UE internal noise from reports.
- Binary analysis cache (`.ucache_z`) avoids re-resolving the same trace.

### Interactive trace viewer (`src/zen/frontend/html/`, `src/zen/trace/trace_viewer_service.*`)
- Timeline: scope-level detail, horizontal zoom/pan, vertical scrolling, viewport-driven loading with pre-computed LOD for responsive navigation of large traces.
- Thread grouping (collapsible sidebar sections) synthesized from name suffixes, natural sort order, visual distinction between lane threads and OS threads.
- Bookmark and region annotations; region categories with per-category toggles; bookmark marker toggle in the toolbar.
- Filterable Logs tab showing captured `UE_LOG` output.
- Stats tab with per-scope aggregate statistics.
- Memory tab with interactive allocation analysis and an allocation size histogram.
- CsvProfiler event parsing and chart UI.

### Other in-branch supporting changes
- **Cross-platform browser launcher** (`browser_launcher.{h,cpp}`) used by `trace serve`.
- **`ReciprocalU64`** fast 64-bit integer division (zencore/intmath) for trace analyzers.
- **`parallelsort`** cross-platform parallel sort helper (zenutil).
- Frontend zip build rule so the viewer's HTML assets are bundled into `zen.exe`.
- `/Zo` flag for better optimized debug info on Windows release builds.
- `trace-tests.cpp` in the `zen-test` harness (harness itself landed on main via #985).

1 files changed, 45 insertions, 23 deletions

diff --git a/src/zen/zen.cpp b/src/zen/zen.cpp
index 984e8589b..02695419e 100644
--- a/src/zen/zen.cpp
+++ b/src/zen/zen.cpp
@@ -21,13 +21,13 @@
 #include "cmds/service_cmd.h"
 #include "cmds/status_cmd.h"
 #include "cmds/top_cmd.h"
-#include "cmds/trace_cmd.h"
 #include "cmds/ui_cmd.h"
 #include "cmds/up_cmd.h"
 #include "cmds/version_cmd.h"
 #include "cmds/vfs_cmd.h"
 #include "cmds/wipe_cmd.h"
 #include "cmds/workspaces_cmd.h"
+#include "trace/trace_cmd.h"
 
 #include <zencore/callstack.h>
 #include <zencore/config.h>
@@ -270,20 +270,34 @@ ZenCmdWithSubCommands::PrintHelp()
 	Options().set_width(TuiConsoleColumns(80));
 	printf("%s\n", Options().help(Groups).c_str());
 
-	// Append subcommand listing.
+	// Append subcommand listing. When a subcommand has aliases, display them as
+	// "name|alias1|alias2" in the left column so callers discover the alternate spellings.
+	auto FormatSubCmdName = [](ZenSubCmdBase& SubCmd) {
+		std::string Name(SubCmd.SubOptions().program());
+		for (const std::string& Alias : SubCmd.Aliases())
+		{
+			Name.push_back('|');
+			Name.append(Alias);
+		}
+		return Name;
+	};
+
+	std::vector<std::string> FormattedNames;
+	FormattedNames.reserve(m_SubCommands.size());
 	size_t MaxNameLen = 0;
 	for (ZenSubCmdBase* SubCmd : m_SubCommands)
 	{
-		MaxNameLen = std::max(MaxNameLen, SubCmd->SubOptions().program().size());
+		FormattedNames.push_back(FormatSubCmdName(*SubCmd));
+		MaxNameLen = std::max(MaxNameLen, FormattedNames.back().size());
 	}
 
 	printf("subcommands:\n");
-	for (ZenSubCmdBase* SubCmd : m_SubCommands)
+	for (size_t i = 0; i < m_SubCommands.size(); ++i)
 	{
 		printf("  %-*s  %s\n",
 			   static_cast<int>(MaxNameLen),
-			   SubCmd->SubOptions().program().c_str(),
-			   std::string(SubCmd->Description()).c_str());
+			   FormattedNames[i].c_str(),
+			   std::string(m_SubCommands[i]->Description()).c_str());
 	}
 	printf("\nFor global options run: zen --help\n");
 }
@@ -308,16 +322,33 @@ ZenCmdWithSubCommands::PrintSubCommandHelp(cxxopts::Options& SubCmdOptions)
 void
 ZenCmdWithSubCommands::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
-	std::vector<cxxopts::Options*> SubOptionPtrs;
-	SubOptionPtrs.reserve(m_SubCommands.size());
-	for (ZenSubCmdBase* SubCmd : m_SubCommands)
-	{
-		SubOptionPtrs.push_back(&SubCmd->SubOptions());
-	}
-
+	ZenSubCmdBase*	   MatchedSubCmd	= nullptr;
 	cxxopts::Options*  MatchedSubOption = nullptr;
 	std::vector<char*> SubCommandArguments;
-	int				   ParentArgc = GetSubCommand(Options(), argc, argv, SubOptionPtrs, MatchedSubOption, SubCommandArguments);
+	int				   ParentArgc = argc;
+	for (int i = 1; i < argc; ++i)
+	{
+		std::string_view Arg(argv[i]);
+		for (ZenSubCmdBase* SubCmd : m_SubCommands)
+		{
+			const bool NameMatch = SubCmd->SubOptions().program() == Arg;
+			const bool AliasMatch =
+				!NameMatch && std::find(SubCmd->Aliases().begin(), SubCmd->Aliases().end(), Arg) != SubCmd->Aliases().end();
+			if (NameMatch || AliasMatch)
+			{
+				MatchedSubCmd	 = SubCmd;
+				MatchedSubOption = &SubCmd->SubOptions();
+				break;
+			}
+		}
+		if (MatchedSubCmd != nullptr)
+		{
+			SubCommandArguments.push_back(argv[0]);
+			std::copy(&argv[i + 1], &argv[argc], std::back_inserter(SubCommandArguments));
+			ParentArgc = i + 1;
+			break;
+		}
+	}
 
 	// Intercept --help/-h in the parent arg range before calling ParseOptions so
 	// we can append subcommand information to the output.  When a subcommand was
@@ -344,15 +375,6 @@ ZenCmdWithSubCommands::Run(const ZenCliOptions& GlobalOptions, int argc, char**
 		throw OptionParseException("No subcommand specified", {});
 	}
 
-	ZenSubCmdBase* MatchedSubCmd = nullptr;
-	for (ZenSubCmdBase* SubCmd : m_SubCommands)
-	{
-		if (&SubCmd->SubOptions() == MatchedSubOption)
-		{
-			MatchedSubCmd = SubCmd;
-			break;
-		}
-	}
 	ZEN_ASSERT(MatchedSubCmd != nullptr);
 
 	// Intercept --help/-h in the subcommand args so we can show combined help