feat(local): Merge storage locations, fix covers and global update

[lalalasupa0]

Description

This PR improves the Local Source experience by fixing storage merging, scoped storage access, update reliability, and file format support.
Resolves #197, #270, #468, #359, #473.

Core Changes:

1. Merged Storage (For Local source to detect manga from both internal and external storage, not just one #197): LocalSource now merges chapter lists from all configured storage roots (Internal + SD Card) into a single manga entry.
2. Reliable Covers (Not loading covers of local source entries from android/data #270): Fixed cover.jpg detection in scoped storage (Android/data).
3. Global Update Fixes (Global updating no refreshing local sources #468, Don't refresh manga from the local source automatically #359):
   • Manual Updates now correctly process LocalSource entries.
   • Automatic Updates now strictly ignore LocalSource entries to prevent data loss if files are temporarily moved/unmounted.
4. APNG & Animation Support (Display APNGs properly #473): registered AnimatedImageDecoder (Coil) in App.kt. This enables support for APNG, Animated WebP, and GIFs (fixing "static image" bugs) on Android 9+.

Technical Details

• App.kt: Added AnimatedImageDecoder.Factory (API 28+) / GifDecoder.Factory to newImageLoader components.
• LibraryUpdateJob.kt:
  • Filter: Excludes local manga if WORK_NAME_AUTO tag is present.
  • Processing: Allows CatalogueSource types.
• LocalSource.kt: Full refactor for UniFile based merging logic.
• TachiyomiImageDecoder.kt: Preserved existing JXL/AVIF handling alongside new animation support.

Checklist

• Tested manually
• Code follows project style

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