feat(simkl): complete Simkl tracking, TV UI, scrobbling, and sync integration

[Himanth-reddy]

Overview

Adds native Simkl tracking, continuous library synchronization, scrobbling, and TV UI integration to ARVIO for Android TV & Mobile.

Key Features & Changes

• Authentication: Native PIN code OAuth flow (POST /oauth/pin) with QR/URL display and background polling.
• Two-Phase Continuous Sync Strategy:
  • Phase 1: Sequential full library fetch for movies, shows, and anime.
  • Phase 2: Lightweight delta synchronization using GET /sync/activities and GET /sync/all-items?date_from=....
  • Activity checks throttled to 15-minute intervals.
• Real-Time Scrobbling: Playback progress scrobbler (POST /scrobble/start, pause, stop) with automatic 5-minute progress intervals.
• Watchlist & History Management:
  • Compliant with official Simkl API schemas (POST /sync/add-to-list for Plan to Watch and POST /sync/history/remove for unwatching).
  • Watch history preservation when untoggling items from watchlist.
• Rate Limiting & Headers: Built-in 1-second POST rate limiter, user agent, and API key interceptor.
• Unit Tests: Full MockK integration test suite covering auth, sync, scrobbler, and error handling.

[Himanth-reddy]

Replaced by standalone PR #560 branched directly off main