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, 124 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/Examples/ExamplePDBSize.cpp b/thirdparty/raw_pdb/src/Examples/ExamplePDBSize.cpp
new file mode 100644
index 000000000..c0a4dc6a4
--- /dev/null
+++ b/thirdparty/raw_pdb/src/Examples/ExamplePDBSize.cpp
@@ -0,0 +1,124 @@
+// 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 "ExampleTimedScope.h"
+#include "PDB_RawFile.h"
+#include "PDB_DBIStream.h"
+
+
+namespace
+{
+	struct Stream
+	{
+		std::string name;
+		uint32_t size;
+	};
+}
+
+
+void ExamplePDBSize(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream);
+void ExamplePDBSize(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream)
+{
+	TimedScope total("\nRunning example \"PDBSize\"");
+
+	std::vector<Stream> streams;
+
+	// print show general statistics
+	printf("General\n");
+	printf("-------\n");
+	{
+		const PDB::SuperBlock* superBlock = rawPdbFile.GetSuperBlock();
+		printf("PDB page size (block size): %u\n", superBlock->blockSize);
+		printf("PDB block count: %u\n", superBlock->blockCount);
+
+		const size_t rawSize = static_cast<size_t>(superBlock->blockSize) * static_cast<size_t>(superBlock->blockCount);
+		printf("PDB raw size: %zu MiB (%zu GiB)\n", rawSize >> 20u, rawSize >> 30u);
+	}
+
+	// print the sizes of all known streams
+	printf("\n");
+	printf("Sizes of known streams\n");
+	printf("----------------------\n");
+	{
+		const uint32_t streamCount = rawPdbFile.GetStreamCount();
+		const uint32_t tpiStreamSize = (streamCount > 2u) ? rawPdbFile.GetStreamSize(2u) : 0u;
+		const uint32_t dbiStreamSize = (streamCount > 3u) ? rawPdbFile.GetStreamSize(3u) : 0u;
+		const uint32_t ipiStreamSize = (streamCount > 4u) ? rawPdbFile.GetStreamSize(4u) : 0u;
+
+		printf("TPI stream size: %u KiB (%u MiB)\n", tpiStreamSize >> 10u, tpiStreamSize >> 20u);
+		printf("DBI stream size: %u KiB (%u MiB)\n", dbiStreamSize >> 10u, dbiStreamSize >> 20u);
+		printf("IPI stream size: %u KiB (%u MiB)\n", ipiStreamSize >> 10u, ipiStreamSize >> 20u);
+
+		streams.push_back(Stream { "TPI", tpiStreamSize });
+		streams.push_back(Stream { "DBI", dbiStreamSize });
+		streams.push_back(Stream { "IPI", ipiStreamSize });
+
+		const uint32_t globalSymbolStreamSize = rawPdbFile.GetStreamSize(dbiStream.GetHeader().globalStreamIndex);
+		const uint32_t publicSymbolStreamSize = rawPdbFile.GetStreamSize(dbiStream.GetHeader().publicStreamIndex);
+		const uint32_t symbolRecordStreamSize = rawPdbFile.GetStreamSize(dbiStream.GetHeader().symbolRecordStreamIndex);
+
+		printf("Global symbol stream size: %u KiB (%u MiB)\n", globalSymbolStreamSize >> 10u, globalSymbolStreamSize >> 20u);
+		printf("Public symbol stream size: %u KiB (%u MiB)\n", publicSymbolStreamSize >> 10u, publicSymbolStreamSize >> 20u);
+		printf("Symbol record stream size: %u KiB (%u MiB)\n", symbolRecordStreamSize >> 10u, symbolRecordStreamSize >> 20u);
+
+		streams.emplace_back(Stream { "Global", globalSymbolStreamSize });
+		streams.emplace_back(Stream { "Public", publicSymbolStreamSize });
+		streams.emplace_back(Stream { "Symbol", symbolRecordStreamSize });
+	}
+
+	// print the sizes of all module streams
+	printf("\n");
+	printf("Sizes of module streams\n");
+	printf("-----------------------\n");
+	{
+		const PDB::ModuleInfoStream moduleInfoStream = dbiStream.CreateModuleInfoStream(rawPdbFile);
+		const PDB::ArrayView<PDB::ModuleInfoStream::Module> modules = moduleInfoStream.GetModules();
+
+		for (const PDB::ModuleInfoStream::Module& module : modules)
+		{
+			const PDB::DBI::ModuleInfo* moduleInfo = module.GetInfo();
+			const char* name = module.GetName().Decay();
+			const char* objectName = module.GetObjectName().Decay();
+
+			const uint16_t streamIndex = module.HasSymbolStream() ? moduleInfo->moduleSymbolStreamIndex : 0u;
+			const uint32_t moduleStreamSize = (streamIndex != 0u) ? rawPdbFile.GetStreamSize(streamIndex) : 0u;
+
+			printf("Module %s (%s) stream size: %u KiB (%u MiB)\n", name, objectName, moduleStreamSize >> 10u, moduleStreamSize >> 20u);
+
+			streams.push_back(Stream { name, moduleStreamSize });
+		}
+	}
+
+	// sort the streams by their size
+	std::sort(streams.begin(), streams.end(), [](const Stream& lhs, const Stream& rhs)
+	{
+		return lhs.size > rhs.size;
+	});
+
+	// log the 20 largest stream
+	{
+		printf("\n");
+		printf("Sizes of 20 largest streams:\n");
+
+		const size_t countToShow = std::min<size_t>(20ul, streams.size());
+		for (size_t i = 0u; i < countToShow; ++i)
+		{
+			const Stream& stream = streams[i];
+			printf("%zu: %u KiB (%u MiB) from stream %s\n", i + 1u, stream.size >> 10u, stream.size >> 20u, stream.name.c_str());
+		}
+	}
+
+	// print the raw stream sizes
+	printf("\n");
+	printf("Raw sizes of all streams\n");
+	printf("------------------------\n");
+	{
+		const uint32_t streamCount = rawPdbFile.GetStreamCount();
+		for (uint32_t i = 0u; i < streamCount; ++i)
+		{
+			const uint32_t streamSize = rawPdbFile.GetStreamSize(i);
+			printf("Stream %u size: %u KiB (%u MiB)\n", i, streamSize >> 10u, streamSize >> 20u);
+		}
+	}
+}