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, 200 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/Examples/ExampleMain.cpp b/thirdparty/raw_pdb/src/Examples/ExampleMain.cpp
new file mode 100644
index 000000000..b4249422f
--- /dev/null
+++ b/thirdparty/raw_pdb/src/Examples/ExampleMain.cpp
@@ -0,0 +1,200 @@
+// Copyright 2011-2022, Molecular Matters GmbH <[email protected]>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "Examples_PCH.h"
+#include "ExampleMemoryMappedFile.h"
+#include "PDB.h"
+#include "PDB_RawFile.h"
+#include "PDB_InfoStream.h"
+#include "PDB_DBIStream.h"
+#include "PDB_TPIStream.h"
+#include "PDB_IPIStream.h"
+#include "PDB_NamesStream.h"
+
+namespace
+{
+	PDB_NO_DISCARD static bool IsError(PDB::ErrorCode errorCode)
+	{
+		switch (errorCode)
+		{
+			case PDB::ErrorCode::Success:
+				return false;
+
+			case PDB::ErrorCode::InvalidSuperBlock:
+				printf("Invalid Superblock\n");
+				return true;
+
+			case PDB::ErrorCode::InvalidFreeBlockMap:
+				printf("Invalid free block map\n");
+				return true;
+
+			case PDB::ErrorCode::InvalidStream:
+				printf("Invalid stream\n");
+				return true;
+
+			case PDB::ErrorCode::InvalidSignature:
+				printf("Invalid stream signature\n");
+				return true;
+
+			case PDB::ErrorCode::InvalidStreamIndex:
+				printf("Invalid stream index\n");
+				return true;
+
+			case PDB::ErrorCode::InvalidDataSize:
+				printf("Invalid data size\n");
+				return true;
+
+			case PDB::ErrorCode::UnknownVersion:
+				printf("Unknown version\n");
+				return true;
+		}
+
+		// only ErrorCode::Success means there wasn't an error, so all other paths have to assume there was an error
+		return true;
+	}
+
+	PDB_NO_DISCARD static bool HasValidDBIStreams(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream)
+	{
+		// check whether the DBI stream offers all sub-streams we need
+		if (IsError(dbiStream.HasValidSymbolRecordStream(rawPdbFile)))
+		{
+			return false;
+		}
+
+		if (IsError(dbiStream.HasValidPublicSymbolStream(rawPdbFile)))
+		{
+			return false;
+		}
+
+		if (IsError(dbiStream.HasValidGlobalSymbolStream(rawPdbFile)))
+		{
+			return false;
+		}
+
+		if (IsError(dbiStream.HasValidSectionContributionStream(rawPdbFile)))
+		{
+			return false;
+		}
+
+		if (IsError(dbiStream.HasValidImageSectionStream(rawPdbFile)))
+		{
+			return false;
+		}
+
+		return true;
+	}
+}
+
+
+// declare all examples
+extern void ExamplePDBSize(const PDB::RawFile&, const PDB::DBIStream&);
+extern void ExampleTPISize(const PDB::TPIStream& tpiStream, const char* outPath);
+extern void ExampleContributions(const PDB::RawFile&, const PDB::DBIStream&);
+extern void ExampleSymbols(const PDB::RawFile&, const PDB::DBIStream&);
+extern void ExampleFunctionSymbols(const PDB::RawFile&, const PDB::DBIStream&);
+extern void ExampleFunctionVariables(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream, const PDB::TPIStream&);
+extern void ExampleLines(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream, const PDB::InfoStream& infoStream);
+extern void ExampleTypes(const PDB::TPIStream&);
+extern void ExampleIPI(const PDB::RawFile& rawPdbFile, const PDB::InfoStream& infoStream, const PDB::TPIStream& tpiStream, const PDB::IPIStream& ipiStream);
+
+int main(int argc, char** argv)
+{
+	if (argc != 2)
+	{
+		printf("Usage: Examples <PDB path>\nError: Incorrect usage\n");
+
+		return 1;
+	}
+
+	printf("Opening PDB file %s\n", argv[1]);
+
+	// try to open the PDB file and check whether all the data we need is available
+	MemoryMappedFile::Handle pdbFile = MemoryMappedFile::Open(argv[1]);
+	if (!pdbFile.baseAddress)
+	{
+		printf("Cannot memory-map file %s\n", argv[1]);
+
+		return 1;
+	}
+
+	if (IsError(PDB::ValidateFile(pdbFile.baseAddress, pdbFile.len)))
+	{
+		MemoryMappedFile::Close(pdbFile);
+
+		return 2;
+	}
+
+	const PDB::RawFile rawPdbFile = PDB::CreateRawFile(pdbFile.baseAddress);
+	if (IsError(PDB::HasValidDBIStream(rawPdbFile)))
+	{
+		MemoryMappedFile::Close(pdbFile);
+
+		return 3;
+	}
+
+	const PDB::InfoStream infoStream(rawPdbFile);
+	if (infoStream.UsesDebugFastLink())
+	{
+		printf("PDB was linked using unsupported option /DEBUG:FASTLINK\n");
+
+		MemoryMappedFile::Close(pdbFile);
+
+		return 4;
+	}
+
+	const auto h = infoStream.GetHeader();
+	printf("Version %u, signature %u, age %u, GUID %08x-%04x-%04x-%02x%02x%02x%02x%02x%02x%02x%02x\n",
+		static_cast<uint32_t>(h->version), h->signature, h->age,
+		h->guid.Data1, h->guid.Data2, h->guid.Data3,
+		h->guid.Data4[0], h->guid.Data4[1], h->guid.Data4[2], h->guid.Data4[3], h->guid.Data4[4], h->guid.Data4[5], h->guid.Data4[6], h->guid.Data4[7]);
+
+	const PDB::DBIStream dbiStream = PDB::CreateDBIStream(rawPdbFile);
+	if (!HasValidDBIStreams(rawPdbFile, dbiStream))
+	{
+		MemoryMappedFile::Close(pdbFile);
+
+		return 5;
+	}
+
+	if (IsError(PDB::HasValidTPIStream(rawPdbFile)))
+	{
+		MemoryMappedFile::Close(pdbFile);
+
+		return 5;
+	}
+	const PDB::TPIStream tpiStream = PDB::CreateTPIStream(rawPdbFile);
+
+	PDB::IPIStream ipiStream;
+
+	// It's perfectly possible that an old PDB does not have an IPI stream.
+	if(infoStream.HasIPIStream())
+	{
+		PDB::ErrorCode error = PDB::HasValidIPIStream(rawPdbFile);
+
+		if (error != PDB::ErrorCode::InvalidStream && IsError(error))
+		{
+			MemoryMappedFile::Close(pdbFile);
+
+			return 5;
+		}
+
+		ipiStream = PDB::CreateIPIStream(rawPdbFile);
+	}	
+
+
+	// run all examples
+	ExamplePDBSize(rawPdbFile, dbiStream);
+	ExampleContributions(rawPdbFile, dbiStream);
+	ExampleSymbols(rawPdbFile, dbiStream);
+	ExampleFunctionSymbols(rawPdbFile, dbiStream);
+	ExampleFunctionVariables(rawPdbFile, dbiStream, tpiStream);
+	ExampleLines(rawPdbFile, dbiStream, infoStream);
+	ExampleTypes(tpiStream);
+	ExampleIPI(rawPdbFile, infoStream, tpiStream, ipiStream);
+	// uncomment to dump type sizes to a CSV
+	// ExampleTPISize(tpiStream, "output.csv");
+
+	MemoryMappedFile::Close(pdbFile);
+
+	return 0;
+}