Implement Lucide Vue icon system and UI improvements

- Replace emoji icons with professional SVG icons from Lucide Vue
- Add collapsible MusicControls with compact top-right collapse button
- Improve icon system with dynamic sizing and proper prop handling
- Disable SSR to prevent hydration issues with audio APIs
- Update IconButton to support both emoji strings and SVG components
- Optimize bottom positioning for expanded vs collapsed states
- Document new icon system in DESIGN_SYSTEM.md

package.json

@@ -17,6 +17,7 @@
   "dependencies": {
     "@vite-pwa/nuxt": "^1.0.4",
     "@vueuse/core": "^10.5.0",
-    "@vueuse/nuxt": "^10.5.0"
+    "@vueuse/nuxt": "^10.5.0",
+    "lucide-vue-next": "^0.536.0"
   }
 }