feat(ci): integrate clang-tidy for changed C/C++ files

[kgeg401]

Summary

• add repository-level .clang-tidy with a minimal enforceable check set
• add .github/workflows/clang_tidy.yml to run on C/C++ and CMake-related changes
• configure CMake to export compile_commands.json and run clang-tidy on changed C/C++ files only
• fail CI for clang-tidy findings via --warnings-as-errors='*'

Notes

• workflow still runs configure on CMake changes even when no C/C++ file changed
• .gitignore is updated to allow tracking .clang-tidy

Fixes #74

[kgeg401]

..

[kgeg401]

Cleaned up PR scope and hardened clang-tidy workflow:\n\n- Removed unrelated FP16 test changes from this PR (keeps overlap out of #116).\n- Kept this PR scoped to .clang-tidy, workflow, and CI plumbing files only.\n- Updated workflow to run clang-tidy only on changed source files that exist in compile_commands.json, with explicit skipped-file reporting and non-failing no-op behavior when no analyzable files are present.