Add Bandcamp/YouTube links on all recs, Fix My Playlist, configurable rec count

- Bandcamp: match artist+song, fall back to artist-only page
- YouTube fallback: if not on Bandcamp, link to YouTube music video search
- Fix My Playlist: AI analyzes playlist, finds outliers, suggests replacements
- User chooses recommendation count (5, 10, 15, 20)

frontend/src/components/RecommendationCard.tsx

@@ -80,7 +80,7 @@ export default function RecommendationCard({ recommendation, onToggleSave, onDis
             </button>
           )}
 
-          {recommendation.bandcamp_url && (
+          {recommendation.bandcamp_url ? (
             <a
               href={recommendation.bandcamp_url}
               target="_blank"
@@ -90,7 +90,17 @@ export default function RecommendationCard({ recommendation, onToggleSave, onDis
             >
               <ExternalLink className="w-4 h-4" />
             </a>
-          )}
+          ) : recommendation.youtube_url ? (
+            <a
+              href={recommendation.youtube_url}
+              target="_blank"
+              rel="noopener noreferrer"
+              className="p-2 rounded-full bg-red-50 text-red-600 hover:bg-red-100 transition-colors"
+              title="Watch on YouTube"
+            >
+              <ExternalLink className="w-4 h-4" />
+            </a>
+          ) : null}
         </div>
       </div>
     </div>