feat: Click album art in DetailPanel to play track

DetailPanel.tsx:
- Added optional onPlay prop to interface
- Album art image now wrapped in clickable container with cursor-pointer
- Hover overlay: semi-transparent black bg with white play triangle icon
- Works for both artwork images and placeholder (treble clef) state
- Placeholder gets hover:bg-white/10 for subtle feedback
- App.tsx: passes handlePlay to DetailPanel onPlay prop

Visual feedback:
- group-hover opacity transition on overlay (0 → 1)
- Play icon: w-12 h-12 white triangle (▶) centered
- Smooth 150ms transition on overlay opacity

frontend/src/App.tsx

@@ -234,6 +234,7 @@ function App() {
           onDelete={handleDelete}
           onUploadArtwork={handleUploadArtwork}
           onRemoveArtwork={handleRemoveArtwork}
+          onPlay={handlePlay}
         />
       )}
 

frontend/src/components/DetailPanel.tsx

@@ -23,6 +23,7 @@ interface Props {
   onDelete: (id: string) => void
   onUploadArtwork: (id: string, file: File) => void
   onRemoveArtwork: (id: string) => void
+  onPlay?: (clip: Clip) => void
 }
 
 const modelName = (modelId: string) => {
@@ -33,7 +34,7 @@ const modelName = (modelId: string) => {
   return names[modelId] || modelId
 }
 
-export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploadArtwork, onRemoveArtwork }: Props) {
+export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploadArtwork, onRemoveArtwork, onPlay }: Props) {
   const artworkInputRef = useRef<HTMLInputElement>(null)
   const [isEditingTitle, setIsEditingTitle] = useState(false)
   const [editTitle, setEditTitle] = useState(clip.title || '')
@@ -146,17 +147,35 @@ export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploa
               </div>
             </div>
             {clip.artwork_filename ? (
+              <div
+                className="relative w-full aspect-square rounded-lg overflow-hidden cursor-pointer group"
+                onClick={() => onPlay?.(clip)}
+              >
                 <img
                   src={`/api/clips/${clip.id}/artwork`}
                   alt="Album art"
-                className="w-full aspect-square rounded-lg object-cover"
+                  className="w-full h-full object-cover"
                 />
+                <div className="absolute inset-0 bg-black/40 opacity-0 group-hover:opacity-100 transition-opacity flex items-center justify-center">
+                  <svg className="w-12 h-12 text-white" fill="currentColor" viewBox="0 0 24 24">
+                    <path d="M8 5v14l11-7z" />
+                  </svg>
+                </div>
+              </div>
             ) : (
-              <div className="w-full aspect-square bg-white/5 rounded-lg flex flex-col items-center justify-center text-lyria-accent/20">
+              <div
+                className="relative w-full aspect-square bg-white/5 rounded-lg flex flex-col items-center justify-center text-lyria-accent/20 cursor-pointer group hover:bg-white/10 transition-colors"
+                onClick={() => onPlay?.(clip)}
+              >
                 <svg className="w-14 h-14" viewBox="0 0 24 24">
                   <text x="12" y="19" textAnchor="middle" fontSize="20" fill="currentColor">𝄞</text>
                 </svg>
                 <span className="text-xs mt-1 text-lyria-muted/40">No album art</span>
+                <div className="absolute inset-0 bg-black/40 opacity-0 group-hover:opacity-100 transition-opacity flex items-center justify-center">
+                  <svg className="w-12 h-12 text-white" fill="currentColor" viewBox="0 0 24 24">
+                    <path d="M8 5v14l11-7z" />
+                  </svg>
+                </div>
               </div>
             )}
             <input