* perf: Optimize get_standard_logging_metadata with set intersection
- Cache StandardLoggingMetadata.__annotations__.keys() as module-level frozenset
- Use set intersection to iterate only keys present in both metadata and supported keys
- Single lookup for user_api_key instead of 3 separate .get() calls
Results:
- get_standard_logging_metadata: 1.55s → 1.41s (9.2% faster)
* test: add unit tests for get_standard_logging_metadata non-string user_api_key handling