The Visual Studio CMake generator does not emit compile_commands.json, so
clangd had no include paths or flags and reported hundreds of false errors.
Add a parallel Ninja config (build-clangd/) that produces the database:
- CMAKE_EXPORT_COMPILE_COMMANDS ON (honored by Ninja, ignored by VS)
- gen-compile-commands.bat configures build-clangd/ under vcvars64
- .clangd points clangd's CompilationDatabase at build-clangd/
- ignore /build-clangd
clangd's clang-cl driver auto-resolves the MSVC/Windows SDK system includes,
so the cl.exe-based database is sufficient.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
