feat: MyAnimeList community score on anime details (#45)

[ProdigyV21]

Closes #45.

Displays a MAL community score badge next to the IMDb badge on anime details pages. Only renders for anime content and only when Jikan returns a score — non-anime and unscored entries see no visual change.

Flow

IMDB id -> ARM API (imdb -> mal_id) -> Jikan v4 (/anime/{mal_id} -> score)

ARVIO already uses the ARM API in SkipIntroRepository for the AniSkip intro-marker feature, so the IMDB to MAL hop is a known working path. Jikan v4 is the unofficial MyAnimeList REST API and is widely used by anime apps for community score display.

Changes

• JikanApi.kt (new) — Retrofit interface with GET /anime/{malId} and response models that deserialize the score field.
• AnimeScoreRepository.kt (new, @singleton) — wraps IMDB to MAL to score with in-memory LRU caching (256 entries each for imdbId -> malId and malId -> score, including negative caching to avoid re-hitting ARM for titles that aren't in its database). Uses withTimeoutOrNull(2_000L) on each hop so slow responses don't stall details load. All exceptions swallowed to null — caller hides the badge.
• AppModule.kt — new Retrofit instance for https://api.jikan.moe/v4/ and @Provides binding for JikanApi, matching the existing ArmApi provider pattern.
• DetailsUiState — new malScore: Double? field (nullable, default null).
• DetailsViewModel — now takes AnimeScoreRepository. Fetches the MAL score in a detached launch off the existing external-IDs resolver, gated on AnimeMapper.isAnimeContentStatic(tmdbId, genreIds, originalLanguage) so we don't hit Jikan for live-action content. Runs in parallel with the main details load — never blocks rendering.
• DetailsScreen — renders a MAL badge in the metadata row after IMDb, only when uiState.malScore > 0.0. Added to both the mobile layout and the TV layout. Uses the MAL brand color #2E51A2 so it's visually distinct from the yellow IMDb badge.

Rate limits

Jikan unofficial rate limit is about 3 req/s, 60 req/min. The LRU cache handles this — a typical session performs at most one Jikan call per unique anime visited, and results persist for the lifetime of the process. Rebrowsing a catalog of anime costs zero network.

Risk

Low. Three entirely new files plus minor additive changes to three existing files. No existing flow is touched; the MAL badge renders only for anime AND only when Jikan returns a score. Jikan being down = no badge; ARM being down = no badge; 2s timeout on each hop means worst case is 4 seconds of background work that never surfaces to the UI.

Test

1. Open an anime title (e.g. Attack on Titan, Demon Slayer, Your Name).
2. Within about 2 seconds of the details loading, a blue "MAL 8.4" style badge should appear after the IMDb badge.
3. Open a live-action title — verify no MAL badge (no Jikan request made either, per the isAnimeContentStatic gate).
4. Open the same anime again — verify it still shows (cache hit, zero network).