- Root cause: Server needed restart to complete initialization
- Startup process syncs data files to DB and loads into memory
- Verified: GET /api/anime returns 192 anime with full metadata
- Added _find_series_directory() to locate series without full rescan
- Added _scan_series_episodes() to scan only target series directory
- Modified _load_episodes() to use targeted scanning instead of anime_service.rescan()
- Added 15 comprehensive unit tests for optimization
- Performance improvement: <1s vs 30-60s for large libraries
- All tests passing (15 new tests + 14 existing background loader tests)
