refactor(audio): Phase 2 — simplify AudioService to thin WaveSurfer wrapper

audioService.ts rewritten from ~850 lines to ~130:
- Remove custom logging system with throttle that suppressed ERROR logs
- Remove AudioContext management entirely (initializeAudioContext,
  handleAudioContextResume, setupAudioContext, shareAudioContextWithWaveSurfer,
  ensureAudioContext). WaveSurfer v7 owns its AudioContext; fighting it caused
  prod/dev divergence and silent failures.
- Replace 5-state InitializationState machine + split promise with a single
  isReady boolean set in the 'ready' event handler
- Remove retry/debounce logic from play() — these are UI concerns
- Remove dead methods: canPlayAudio (always returned true), getWaveSurferVersion,
  updatePlayerState, getAudioContextState, setLogLevel
- Extract destroyWaveSurfer() helper so cleanup is one place
- MiniPlayer now passes songId/bandId to play() (was calling with no args)
- SongPage spacebar handler simplified: just checks isReady from hook
- SongPage no longer imports audioService directly

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

web/src/components/MiniPlayer.tsx

@@ -94,7 +94,9 @@ export function MiniPlayer() {
           if (isPlaying) {
             audioService.pause();
           } else {
-            audioService.play();
+            audioService.play(currentSongId, currentBandId).catch(err => {
+              console.warn('MiniPlayer playback failed:', err);
+            });
           }
         }}
         style={