feat(web): integrate Simkl tracking client and API proxy

[Himanth-reddy]

Summary of Changes

This PR adds client-side and server-side Next.js support for Simkl tracking in the ARVIO Web application.

1. Simkl Web Client (web/lib/simkl.ts)

• Implemented SimklClient class adhering to the SyncClient interface.
• Supported PIN device authentication (beginPinAuth, pollPinToken).
• Implemented real-time scrobbling (scrobble for start, pause, stop) with progress normalization.
• Implemented watched history fetching and watchlist management (addToWatchlist, removeFromWatchlist, addToHistory, removeFromHistory).

2. Next.js API Proxy (web/app/api/simkl/[...path]/route.ts)

• Created server-side API proxy route /api/simkl/... to route API requests securely through Netlify backend (auth.arvio.tv) or direct Simkl endpoints without exposing client secrets.

3. Tracking Provider Integration (web/lib/sync.ts)

• Updated SyncProvider type to include "simkl".
• Routed activeSyncProvider() and syncClient() to support simklClient.

Testing & Verification

• npx tsc --noEmit passed with 0 errors.

[Himanth-reddy]

Superseded by #558 (from Himanth-reddy:simkl/web into main)