feat(dl): add --animeapi and --enrich options for anime metadata and tagging

Add AnimeAPI integration to resolve anime database IDs (MAL, AniList, Kitsu, etc.) to TMDB/IMDB/TVDB for MKV tagging. The --enrich flag overrides show title and fills in year when missing from the service.

- Add animeapi-py dependency for cross-platform anime ID resolution
- Add --animeapi option (e.g. mal:12345, anilist:98765, defaults to MAL)
- Add --enrich flag to override title/year from external sources
- Remove --tmdb-name and --tmdb-year in favor of unified --enrich
- Update REST API params and docs to match

docs/API.md

@@ -231,9 +231,9 @@ Start a download job. Returns immediately with a job ID (HTTP 202).
 | `tag` | string | `null` | Override group tag |
 | `repack` | boolean | `false` | Add REPACK tag to filename |
 | `tmdb_id` | int | `null` | Use specific TMDB ID for tagging |
-| `tmdb_name` | boolean | `false` | Rename titles using TMDB name |
-| `tmdb_year` | boolean | `false` | Use TMDB release year |
 | `imdb_id` | string | `null` | Use specific IMDB ID (e.g., `tt1375666`) |
+| `animeapi_id` | string | `null` | Anime database ID via AnimeAPI (e.g., `mal:12345`) |
+| `enrich` | boolean | `false` | Override show title and year from external source |
 | `no_folder` | boolean | `false` | Disable folder creation for TV shows |
 | `no_source` | boolean | `false` | Remove source tag from filename |
 | `no_mux` | boolean | `false` | Do not mux tracks into container |