ci: add sanitizer workflows

[cnaples79]

Summary

• add a dedicated GitHub Actions workflow that runs address-, memory-, and thread-sanitized builds
• configure clang/clang++ with the appropriate sanitizer compile/link flags and reuse the project’s cmake flow
• reuse the existing googletest fetch so sanitizer runs execute the ctest target

Rationale

Issue #457 covers the lack of sanitizer coverage. Running ASan/MSan/TSan in CI helps catch undefined behavior early without altering the main build pipeline.

Fixes #457