feat: Smart play/pause overlay on DetailPanel album art

DetailPanel.tsx:
- Added isPlaying and currentClipId props to track playback state
- Added onTogglePlay prop for pausing currently-playing track
- Album art click handler now smart:
  * If this track IS playing → pause it (onTogglePlay)
  * If this track is NOT playing → play it (onPlay)
- Hover overlay icon adapts dynamically:
  * Currently playing + hover → shows PAUSE icon (⏸)
  * Not playing + hover → shows PLAY icon (▶)
- Works for both artwork images and placeholder state

App.tsx:
- Passes isPlaying, currentClipId, and onTogglePlay to DetailPanel

Visual states:
- Different track in panel: ▶ on hover (click to play)
- Same track playing: ⏸ on hover (click to pause)
- Same track paused: ▶ on hover (click to resume)

frontend/src/App.tsx

@@ -229,12 +229,15 @@ function App() {
       {selectedClip && (
         <DetailPanel
           clip={selectedClip}
+          isPlaying={isPlaying}
+          currentClipId={currentClip?.id}
           onClose={() => setSelectedClip(null)}
           onRename={handleRename}
           onDelete={handleDelete}
           onUploadArtwork={handleUploadArtwork}
           onRemoveArtwork={handleRemoveArtwork}
           onPlay={handlePlay}
+          onTogglePlay={() => setIsPlaying(!isPlaying)}
         />
       )}
 

frontend/src/components/DetailPanel.tsx

@@ -18,12 +18,15 @@ interface Clip {
 
 interface Props {
   clip: Clip
+  isPlaying: boolean
+  currentClipId?: string
   onClose: () => void
   onRename: (id: string, title: string) => void
   onDelete: (id: string) => void
   onUploadArtwork: (id: string, file: File) => void
   onRemoveArtwork: (id: string) => void
   onPlay?: (clip: Clip) => void
+  onTogglePlay?: () => void
 }
 
 const modelName = (modelId: string) => {
@@ -34,7 +37,7 @@ const modelName = (modelId: string) => {
   return names[modelId] || modelId
 }
 
-export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploadArtwork, onRemoveArtwork, onPlay }: Props) {
+export default function DetailPanel({ clip, isPlaying, currentClipId, onClose, onRename, onDelete, onUploadArtwork, onRemoveArtwork, onPlay, onTogglePlay }: Props) {
   const artworkInputRef = useRef<HTMLInputElement>(null)
   const [isEditingTitle, setIsEditingTitle] = useState(false)
   const [editTitle, setEditTitle] = useState(clip.title || '')
@@ -149,7 +152,13 @@ export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploa
             {clip.artwork_filename ? (
               <div
                 className="relative w-full aspect-square rounded-lg overflow-hidden cursor-pointer group"
-                onClick={() => onPlay?.(clip)}
+                onClick={() => {
+                  if (currentClipId === clip.id && isPlaying) {
+                    onTogglePlay?.()
+                  } else {
+                    onPlay?.(clip)
+                  }
+                }}
               >
                 <img
                   src={`/api/clips/${clip.id}/artwork`}
@@ -157,24 +166,42 @@ export default function DetailPanel({ clip, onClose, onRename, onDelete, onUploa
                   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">
+                  {currentClipId === clip.id && isPlaying ? (
+                    <svg className="w-12 h-12 text-white" fill="currentColor" viewBox="0 0 24 24">
+                      <path d="M6 19h4V5H6v14zm8-14v14h4V5h-4z" />
+                    </svg>
+                  ) : (
                     <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="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)}
+                onClick={() => {
+                  if (currentClipId === clip.id && isPlaying) {
+                    onTogglePlay?.()
+                  } else {
+                    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">
+                  {currentClipId === clip.id && isPlaying ? (
+                    <svg className="w-12 h-12 text-white" fill="currentColor" viewBox="0 0 24 24">
+                      <path d="M6 19h4V5H6v14zm8-14v14h4V5h-4z" />
+                    </svg>
+                  ) : (
                     <svg className="w-12 h-12 text-white" fill="currentColor" viewBox="0 0 24 24">
                       <path d="M8 5v14l11-7z" />
                     </svg>
+                  )}
                 </div>
               </div>
             )}