clang-cl keeps the MSVC ABI, so the Windows SDK, the vcpkg packages and
D3D12 all still link; only the front end changes. That front end is the
one whose module support has been giving way - global module fragment
merging and type completeness at a template's instantiation point.
Switches the job to Ninja, which is where CMake's module scanning is best
supported, with vcvars64 for the SDK paths. Ninja is single-config, so
the artifacts move from build/bin/<config>/ to build/bin/.
CMakeLists: the MSVC-only blocks tested CMAKE_CXX_COMPILER_ID, which
clang-cl reports as Clang, so the version resource, the icon and /utf-8
would have been dropped silently. They test MSVC now, which is true for
both. /MAP and /MP stay behind a real-MSVC check - the first is a
link.exe spelling, the second clang-cl rejects.
Linux CI switches to clang 22; fixes what that exposed - export on
out-of-line member definitions, missing std includes, missing glm
imports. GCC 16 still builds.
