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, 151 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/PDB_ModuleLineStream.h b/thirdparty/raw_pdb/src/PDB_ModuleLineStream.h
new file mode 100644
index 000000000..d1148cc0c
--- /dev/null
+++ b/thirdparty/raw_pdb/src/PDB_ModuleLineStream.h
@@ -0,0 +1,151 @@
+// 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)
+
+#pragma once
+
+#include "Foundation/PDB_Macros.h"
+#include "Foundation/PDB_BitUtil.h"
+#include "PDB_DBITypes.h"
+#include "PDB_Util.h"
+#include "PDB_CoalescedMSFStream.h"
+
+
+namespace PDB
+{
+	class RawFile;
+
+	class PDB_NO_DISCARD ModuleLineStream
+	{
+	public:
+		ModuleLineStream(void) PDB_NO_EXCEPT;
+		explicit ModuleLineStream(const RawFile& file, uint16_t streamIndex, uint32_t streamSize, size_t c13LineInfoOffset) PDB_NO_EXCEPT;
+
+		PDB_DEFAULT_MOVE(ModuleLineStream);
+
+		template <typename F>
+		void ForEachSection(F&& functor) const PDB_NO_EXCEPT
+		{
+			size_t offset = m_c13LineInfoOffset;
+
+			// read the line stream sections
+			while (offset < m_stream.GetSize())
+			{
+				const CodeView::DBI::LineSection* section = m_stream.GetDataAtOffset<const CodeView::DBI::LineSection>(offset);
+
+				functor(section);
+
+				offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + section->header.size, 4u);
+			}
+		}
+
+		template <typename F>
+		void ForEachLinesBlock(const CodeView::DBI::LineSection* section, F&& functor) const PDB_NO_EXCEPT
+		{
+			PDB_ASSERT(section->header.kind == CodeView::DBI::DebugSubsectionKind::S_LINES,
+				"DebugSubsectionHeader::Kind %X != S_LINES (%X)", 
+				static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::DebugSubsectionKind::S_LINES));
+
+			size_t offset = m_stream.GetPointerOffset(section);
+			const size_t headerEnd = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + section->header.size, 4u);
+
+			offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + sizeof(CodeView::DBI::LinesHeader), 4u);
+
+			// read all blocks of lines
+			while (offset < headerEnd)
+			{
+				const CodeView::DBI::LinesFileBlockHeader* linesBlockHeader = m_stream.GetDataAtOffset<const CodeView::DBI::LinesFileBlockHeader>(offset);
+				const CodeView::DBI::Line* blockLines = m_stream.GetDataAtOffset<const CodeView::DBI::Line>(offset + sizeof(CodeView::DBI::LinesFileBlockHeader));
+
+				const size_t blockColumnsOffset = sizeof(CodeView::DBI::LinesFileBlockHeader) + (linesBlockHeader->numLines * (sizeof(CodeView::DBI::Line)));
+				const CodeView::DBI::Column* blockColumns = blockColumnsOffset < linesBlockHeader->size ? m_stream.GetDataAtOffset<const CodeView::DBI::Column>(offset) : nullptr;
+
+				functor(linesBlockHeader, blockLines, blockColumns);
+
+				offset = BitUtil::RoundUpToMultiple<size_t>(offset + linesBlockHeader->size, 4u);
+			}
+
+			PDB_ASSERT(offset == headerEnd, "Mismatch between offset %zu and header end %zu when reading lines blocks", offset, headerEnd);
+		}
+
+		template <typename F>
+		void ForEachFileChecksum(const CodeView::DBI::LineSection* section, F&& functor) const PDB_NO_EXCEPT
+		{
+			PDB_ASSERT(section->header.kind == CodeView::DBI::DebugSubsectionKind::S_FILECHECKSUMS,
+				"DebugSubsectionHeader::Kind %X != S_FILECHECKSUMS (%X)", 
+				static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::DebugSubsectionKind::S_FILECHECKSUMS));
+
+			size_t offset = m_stream.GetPointerOffset(section);
+			const size_t headerEnd = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + section->header.size, 4u);
+
+			offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader), 4u);
+
+			// read all file checksums
+			while (offset < headerEnd)
+			{
+				const CodeView::DBI::FileChecksumHeader* fileChecksumHeader = m_stream.GetDataAtOffset<const CodeView::DBI::FileChecksumHeader>(offset);
+
+				functor(fileChecksumHeader);
+
+				offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::FileChecksumHeader) + fileChecksumHeader->checksumSize, 4u);
+			}
+
+			PDB_ASSERT(offset == headerEnd, "Mismatch between offset %zu and header end %zu when reading file checksums", offset, headerEnd);
+		}
+
+		template <typename F>
+		void ForEachInlineeSourceLine(const CodeView::DBI::LineSection* section, F&& functor) const PDB_NO_EXCEPT
+		{
+			PDB_ASSERT(section->header.kind == CodeView::DBI::DebugSubsectionKind::S_INLINEELINES,
+				"DebugSubsectionHeader::Kind %X != S_INLINEELINES (%X)", 
+				static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::DebugSubsectionKind::S_INLINEELINES));
+
+			PDB_ASSERT(section->inlineeHeader.kind == CodeView::DBI::InlineeSourceLineKind::Signature,
+				"InlineeSourceLineKind %X != :InlineeSourceLineKind::Signature (%X)", static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::InlineeSourceLineKind::Signature));
+
+			size_t offset = m_stream.GetPointerOffset(section);
+			const size_t headerEnd = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + section->header.size, 4u);
+
+			offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + sizeof(CodeView::DBI::InlineeSourceLineHeader), 4u);
+
+			// read all file checksums
+			while (offset < headerEnd)
+			{
+				const CodeView::DBI::InlineeSourceLine* inlineeSourceLine = m_stream.GetDataAtOffset<const CodeView::DBI::InlineeSourceLine>(offset);
+
+				functor(inlineeSourceLine);
+
+				offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::InlineeSourceLine), 4u);
+			}
+		}
+
+		template <typename F>
+		void ForEachInlineeSourceLineEx(const CodeView::DBI::LineSection* section, F&& functor) const PDB_NO_EXCEPT
+		{
+			PDB_ASSERT(section->header.kind == CodeView::DBI::DebugSubsectionKind::S_INLINEELINES,
+				"DebugSubsectionHeader::Kind %X != S_INLINEELINES (%X)", static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::DebugSubsectionKind::S_INLINEELINES));
+
+			PDB_ASSERT(section->inlineeHeader.kind == CodeView::DBI::InlineeSourceLineKind::SignatureEx,
+				"InlineeSourceLineKind %X != :InlineeSourceLineKind::SignatureEx (%X)", static_cast<uint32_t>(section->header.kind), static_cast<uint32_t>(CodeView::DBI::InlineeSourceLineKind::SignatureEx));
+
+			size_t offset = m_stream.GetPointerOffset(section);
+			const size_t headerEnd = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + section->header.size, 4u);
+
+			offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::DebugSubsectionHeader) + sizeof(CodeView::DBI::InlineeSourceLineHeader), 4u);
+
+			// read all file checksums
+			while (offset < headerEnd)
+			{
+				const CodeView::DBI::InlineeSourceLineEx* inlineeSourceLineEx = m_stream.GetDataAtOffset<const CodeView::DBI::InlineeSourceLineEx>(offset);
+
+				functor(inlineeSourceLineEx);
+
+				offset = BitUtil::RoundUpToMultiple<size_t>(offset + sizeof(CodeView::DBI::InlineeSourceLineEx) + (inlineeSourceLineEx->extraLines * sizeof(uint32_t)), 4u);
+			}
+		}
+	private:
+		CoalescedMSFStream m_stream;
+		size_t m_c13LineInfoOffset;
+
+		PDB_DISABLE_COPY(ModuleLineStream);
+	};
+}