- Add create_minimal_nfo() method to NFOService for fallback when TMDB lookup fails
- Update API endpoints (single and batch) to use minimal NFO fallback on TMDBAPIError
- Document fallback behavior in NFO_GUIDE.md section 3.6
- Add unit tests for minimal NFO creation (11 tests passing)
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
