Backend:
- winamp.GetCurrentFile() reads file path via IPC_GETPLAYLISTFILE (211)
  + ReadProcessMemory, same pattern as playlist titles
- internal/rating: Get/Set POPM frame via bogem/id3v2
  - Email: rating@winamp.com (Winamp standard)
  - Byte scale: 0/1/64/128/196/255 = 0-5 stars
  - Compatible with Windows Explorer and Winamp
- GET /api/rating -> {stars: N}
- POST /api/rating {stars: N} -> writes POPM, returns {stars: N}

Frontend:
- 5 stars in track-info, gold when lit
- Fetched automatically on track change
- Tap to rate; tap same star again to remove rating
- Optimistic update with revert on error

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>