Implement SharedArtworkContentProvider to centralize and secure alb…

[theovilardo]

…um art distribution across the system and external controllers.

Core Architecture & Artwork Sharing

• SharedArtworkContentProvider: Introduced a new ContentProvider to handle artwork requests via a dedicated authority (${applicationId}.artwork). It provides read-only access to cached album art files, improving compatibility with system media style and external metadata consumers.
• URI Resolution: Implemented robust URI building and parsing logic within the provider to handle song-specific artwork requests, including support for cache-busting tokens (?t=).
• Manifest Integration: Registered the new provider with exported="true" to allow cross-process artwork access.

Artwork Utilities & Optimization

• LocalArtworkUri Enhancements:
  • Added support for detecting and parsing "volatile" artwork URIs (legacy cache files and new shared content URIs).
  • Implemented extractCacheBustToken to preserve timestamp metadata during URI transformations.
  • Refactored resolveSongArtworkUri to handle transitions from volatile or legacy URIs to stable internal URI formats.
• MediaItem Mapping: Updated MediaItemBuilder to use SharedArtworkContentProvider URIs when exposing artwork to external controllers, ensuring consistent image loading in notifications and Wear OS.

Reliability & Testing

• Unit Tests:
  • Added SharedArtworkContentProviderTest to verify authority building, URI construction, and song ID parsing.
  • Expanded LocalArtworkUriTest to cover legacy cache filename parsing, shared URI resolution, and cache-bust token extraction.
• Security: Restricted SharedArtworkContentProvider to read-only mode and validated file paths to ensure only legitimate cached artwork is served.