feat(renderer): audio waveform player with WaveSurfer.js (M10.8)

- Lazy-loads WaveSurfer.js on first audio render
- Bitcoin orange waveform on dark background
- Click-to-seek, play/pause, time display
- Responsive width, touch-friendly

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

packages/app/package.json

@@ -29,7 +29,8 @@
     "pinia": "^3.0.4",
     "plyr": "^3.8.4",
     "vue": "^3.5.29",
-    "vue-router": "^5.0.3"
+    "vue-router": "^5.0.3",
+    "wavesurfer.js": "^7.12.1"
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",