Add Bandcamp search and Listening Room page

Implement Bandcamp search service with autocomplete API and HTML
scraping fallback. Add /api/bandcamp/search and /api/bandcamp/embed
endpoints. Create Listening Room page with search, embedded player,
and queue management. Add navigation entry and Bandcamp link on
recommendation cards.

frontend/src/components/RecommendationCard.tsx

@@ -1,4 +1,5 @@
-import { Heart, ExternalLink, Music } from 'lucide-react'
+import { Heart, ExternalLink, Music, Headphones } from 'lucide-react'
+import { Link } from 'react-router-dom'
 import type { RecommendationItem } from '../lib/api'
 
 interface Props {
@@ -71,6 +72,14 @@ export default function RecommendationCard({ recommendation, onToggleSave, savin
               <ExternalLink className="w-4 h-4" />
             </a>
           )}
+
+          <Link
+            to={`/listen?q=${encodeURIComponent(`${recommendation.artist} ${recommendation.title}`)}`}
+            className="p-2 rounded-full bg-purple-50 text-purple-400 hover:bg-purple-100 hover:text-purple transition-colors"
+            title="Find on Bandcamp"
+          >
+            <Headphones className="w-4 h-4" />
+          </Link>
         </div>
       </div>
     </div>