Canvas / viz:
- Idle animation when Winamp stopped/paused: slow sine-wave breathing
  across bars at low amplitude, dim colours — canvas is never dead-black
- 'PLAY' label overlay when stopped, 'NO SIGNAL' when WS disconnected
- hasSignal check: viz data must be < 1.5s old AND Winamp playing
- DPR resize uses Math.round() to avoid sub-pixel canvas size mismatch
- Peak indicators fade quickly in idle mode

winamp.go:
- GetPosition: clamp 0xFFFFFFFF sentinel at source (> 0xF0000000 → 0)
  instead of in server.go; also removed redundant clamp from statusMsg
- GetTitle: use strings.LastIndex/Index instead of hand-rolled helpers
  Returns empty string when window title is just 'Winamp' (stopped/empty)
  Playlist prefix strip is now bounded (dot <= 4) so track titles with
  '. ' in them are not accidentally trimmed

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