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, 100 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/Examples/ExampleMemoryMappedFile.cpp b/thirdparty/raw_pdb/src/Examples/ExampleMemoryMappedFile.cpp
new file mode 100644
index 000000000..4b46b4bab
--- /dev/null
+++ b/thirdparty/raw_pdb/src/Examples/ExampleMemoryMappedFile.cpp
@@ -0,0 +1,100 @@
+// 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"
+
+
+MemoryMappedFile::Handle MemoryMappedFile::Open(const char* path)
+{
+#ifdef _WIN32
+	void* file = CreateFileA(path, GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, nullptr);
+
+	if (file == INVALID_HANDLE_VALUE)
+	{
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* fileMapping = CreateFileMappingW(file, nullptr, PAGE_READONLY, 0, 0, nullptr);
+
+	if (fileMapping == nullptr)
+	{
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* baseAddress = MapViewOfFile(fileMapping, FILE_MAP_READ, 0, 0, 0);
+
+	if (baseAddress == nullptr)
+	{
+		CloseHandle(fileMapping);
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	BY_HANDLE_FILE_INFORMATION fileInformation;
+	const bool getInformationResult = GetFileInformationByHandle(file, &fileInformation);
+	if (!getInformationResult)
+	{
+		UnmapViewOfFile(baseAddress);
+		CloseHandle(fileMapping);
+		CloseHandle(file);
+
+		return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	const size_t fileSizeHighBytes = static_cast<size_t>(fileInformation.nFileSizeHigh) << 32;
+	const size_t fileSizeLowBytes = fileInformation.nFileSizeLow;
+	const size_t fileSize = fileSizeHighBytes | fileSizeLowBytes;
+	return Handle { file, fileMapping, baseAddress, fileSize };
+#else
+	struct stat fileSb;
+
+	int file = open(path, O_RDONLY);
+
+	if (file == INVALID_HANDLE_VALUE)
+	{
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	if (fstat(file, &fileSb) == -1)
+	{
+		close(file);
+
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	void* baseAddress = mmap(nullptr, fileSb.st_size, PROT_READ, MAP_PRIVATE, file, 0);
+
+	if (baseAddress == MAP_FAILED)
+	{
+		close(file);
+
+		return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
+	}
+
+	return Handle { file, baseAddress, static_cast<size_t>(fileSb.st_size) };
+#endif
+}
+
+
+void MemoryMappedFile::Close(Handle& handle)
+{
+#ifdef _WIN32
+	UnmapViewOfFile(handle.baseAddress);
+	CloseHandle(handle.fileMapping);
+	CloseHandle(handle.file);
+
+	handle.file = nullptr;
+	handle.fileMapping = nullptr;
+#else
+	munmap(handle.baseAddress, handle.len);
+	close(handle.file);
+
+	handle.file = 0;
+#endif
+
+	handle.baseAddress = nullptr;
+}