The PR build (ci-pull-request.yml) only runs Debian/Fedora. Platform-specific compile/link failures therefore only surface after merge in the nightly/RC — e.g. the AppleClang constexpr error, the Assimp bundled-zlib break on the macOS SDK, and the Win-ARM64 LNK2001. All of those cost a full RC cycle to catch.

Change

Make the build path-aware in ci-pull-request.yml:

• Add a code output to the detect job — true when src/**, deps/**, **/CMakeLists.txt or version.inc change (deps always count → never skipped).
• Run macOS (15 ARM Universal) + Windows (2022 x64) when code == true.
• Doc-only and most workflow-only PRs still don't trigger any build (paths filter); pure packaging changes still only run the relevant Linux job.

Trade-off: src/deps PRs become multi-platform (slower), but platform breakage is caught in the PR instead of after merge.