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, 238 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/Examples/ExampleSymbols.cpp b/thirdparty/raw_pdb/src/Examples/ExampleSymbols.cpp
new file mode 100644
index 000000000..c1b2ef8ac
--- /dev/null
+++ b/thirdparty/raw_pdb/src/Examples/ExampleSymbols.cpp
@@ -0,0 +1,238 @@
+// 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
+{
+	// we don't have to store std::string in the symbols, since all the data is memory-mapped anyway.
+	// we do it in this example to ensure that we don't "cheat" when reading the PDB file. memory-mapped data will only
+	// be faulted into the process once it's touched, so actually copying the string data makes us touch the needed data,
+	// giving us a real performance measurement.
+	struct Symbol
+	{
+		std::string name;
+		uint32_t rva;
+	};
+}
+
+
+void ExampleSymbols(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream);
+void ExampleSymbols(const PDB::RawFile& rawPdbFile, const PDB::DBIStream& dbiStream)
+{
+	TimedScope total("\nRunning example \"Symbols\"");
+
+	// in order to keep the example easy to understand, we load the PDB data serially.
+	// note that this can be improved a lot by reading streams concurrently.
+
+	// prepare the image section stream first. it is needed for converting section + offset into an RVA
+	TimedScope sectionScope("Reading image section stream");
+	const PDB::ImageSectionStream imageSectionStream = dbiStream.CreateImageSectionStream(rawPdbFile);
+	sectionScope.Done();
+
+
+	// prepare the module info stream for matching contributions against files
+	TimedScope moduleScope("Reading module info stream");
+	const PDB::ModuleInfoStream moduleInfoStream = dbiStream.CreateModuleInfoStream(rawPdbFile);
+	moduleScope.Done();
+
+
+	// prepare symbol record stream needed by both public and global streams
+	TimedScope symbolStreamScope("Reading symbol record stream");
+	const PDB::CoalescedMSFStream symbolRecordStream = dbiStream.CreateSymbolRecordStream(rawPdbFile);
+	symbolStreamScope.Done();
+
+	std::vector<Symbol> symbols;
+
+	// read public symbols
+	TimedScope publicScope("Reading public symbol stream");
+	const PDB::PublicSymbolStream publicSymbolStream = dbiStream.CreatePublicSymbolStream(rawPdbFile);
+	publicScope.Done();
+	{
+		TimedScope scope("Storing public symbols");
+
+		const PDB::ArrayView<PDB::HashRecord> hashRecords = publicSymbolStream.GetRecords();
+		const size_t count = hashRecords.GetLength();
+
+		symbols.reserve(count);
+
+		for (const PDB::HashRecord& hashRecord : hashRecords)
+		{
+			const PDB::CodeView::DBI::Record* record = publicSymbolStream.GetRecord(symbolRecordStream, hashRecord);
+			if (record->header.kind != PDB::CodeView::DBI::SymbolRecordKind::S_PUB32)
+			{
+				// normally, a PDB only contains S_PUB32 symbols in the public symbol stream, but we have seen PDBs that also store S_CONSTANT as public symbols.
+				// ignore these.
+				continue;
+			}
+
+			const uint32_t rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_PUB32.section, record->data.S_PUB32.offset);
+			if (rva == 0u)
+			{
+				// certain symbols (e.g. control-flow guard symbols) don't have a valid RVA, ignore those
+				continue;
+			}
+
+			symbols.push_back(Symbol { record->data.S_PUB32.name, rva });
+		}
+
+		scope.Done(count);
+	}
+
+
+	// read global symbols
+	TimedScope globalScope("Reading global symbol stream");
+	const PDB::GlobalSymbolStream globalSymbolStream = dbiStream.CreateGlobalSymbolStream(rawPdbFile);
+	globalScope.Done();
+	{
+		TimedScope scope("Storing global symbols");
+
+		const PDB::ArrayView<PDB::HashRecord> hashRecords = globalSymbolStream.GetRecords();
+		const size_t count = hashRecords.GetLength();
+
+		symbols.reserve(symbols.size() + count);
+
+		for (const PDB::HashRecord& hashRecord : hashRecords)
+		{
+			const PDB::CodeView::DBI::Record* record = globalSymbolStream.GetRecord(symbolRecordStream, hashRecord);
+
+			const char* name = nullptr;
+			uint32_t rva = 0u;
+			if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_GDATA32)
+			{
+				name = record->data.S_GDATA32.name;
+				rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_GDATA32.section, record->data.S_GDATA32.offset);
+			}
+			else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_GTHREAD32)
+			{
+				name = record->data.S_GTHREAD32.name;
+				rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_GTHREAD32.section, record->data.S_GTHREAD32.offset);
+			}
+			else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LDATA32)
+			{
+				name = record->data.S_LDATA32.name;
+				rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LDATA32.section, record->data.S_LDATA32.offset);
+			}
+			else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LTHREAD32)
+			{
+				name = record->data.S_LTHREAD32.name;
+				rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LTHREAD32.section, record->data.S_LTHREAD32.offset);
+			}
+			else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_UDT)
+			{
+				name = record->data.S_UDT.name;
+			}
+			else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_UDT_ST)
+			{
+				name = record->data.S_UDT_ST.name;
+			}
+
+			if (rva == 0u)
+			{
+				// certain symbols (e.g. control-flow guard symbols) don't have a valid RVA, ignore those
+				continue;
+			}
+
+			symbols.push_back(Symbol { name, rva });
+		}
+
+		scope.Done(count);
+	}
+
+
+	// read module symbols
+	{
+		TimedScope scope("Storing symbols from modules");
+
+		const PDB::ArrayView<PDB::ModuleInfoStream::Module> modules = moduleInfoStream.GetModules();
+
+		for (const PDB::ModuleInfoStream::Module& module : modules)
+		{
+			if (!module.HasSymbolStream())
+			{
+				continue;
+			}
+
+			const PDB::ModuleSymbolStream moduleSymbolStream = module.CreateSymbolStream(rawPdbFile);
+			moduleSymbolStream.ForEachSymbol([&symbols, &imageSectionStream](const PDB::CodeView::DBI::Record* record)
+			{
+				const char* name = nullptr;
+				uint32_t rva = 0u;
+				if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_THUNK32)
+				{
+					if (record->data.S_THUNK32.thunk == PDB::CodeView::DBI::ThunkOrdinal::TrampolineIncremental)
+					{
+						// we have never seen incremental linking thunks stored inside a S_THUNK32 symbol, but better be safe than sorry
+						name = "ILT";
+						rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_THUNK32.section, record->data.S_THUNK32.offset);
+					}
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_TRAMPOLINE)
+				{
+					// incremental linking thunks are stored in the linker module
+					name = "ILT";
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_TRAMPOLINE.thunkSection, record->data.S_TRAMPOLINE.thunkOffset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_BLOCK32)
+				{
+					// blocks never store a name and are only stored for indicating whether other symbols are children of this block
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LABEL32)
+				{
+					// labels don't have a name
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LPROC32)
+				{
+					name = record->data.S_LPROC32.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LPROC32.section, record->data.S_LPROC32.offset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_GPROC32)
+				{
+					name = record->data.S_GPROC32.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_GPROC32.section, record->data.S_GPROC32.offset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LPROC32_ID)
+				{
+					name = record->data.S_LPROC32_ID.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LPROC32_ID.section, record->data.S_LPROC32_ID.offset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_GPROC32_ID)
+				{
+					name = record->data.S_GPROC32_ID.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_GPROC32_ID.section, record->data.S_GPROC32_ID.offset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_REGREL32)
+				{
+					name = record->data.S_REGREL32.name;
+					// You can only get the address while running the program by checking the register value and adding the offset
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LDATA32)
+				{
+					name = record->data.S_LDATA32.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LDATA32.section, record->data.S_LDATA32.offset);
+				}
+				else if (record->header.kind == PDB::CodeView::DBI::SymbolRecordKind::S_LTHREAD32)
+				{
+					name = record->data.S_LTHREAD32.name;
+					rva = imageSectionStream.ConvertSectionOffsetToRVA(record->data.S_LTHREAD32.section, record->data.S_LTHREAD32.offset);
+				}
+
+				if (rva == 0u)
+				{
+					// certain symbols (e.g. control-flow guard symbols) don't have a valid RVA, ignore those
+					return;
+				}
+
+				symbols.push_back(Symbol { name, rva });
+			});
+		}
+
+		scope.Done(modules.GetLength());
+	}
+
+	total.Done(symbols.size());
+}