feat: show waveform in collapsed state

Changes:
- Waveform canvas now displays even when track is collapsed
- Only the upload placeholder is hidden when collapsed
- Gives better visual overview when tracks are minimized
- Similar to DAWs like Ableton Live

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/tracks/Track.tsx

@@ -81,7 +81,7 @@ export function Track({
 
   // Draw waveform
   React.useEffect(() => {
-    if (!track.audioBuffer || !canvasRef.current || track.collapsed) return;
+    if (!track.audioBuffer || !canvasRef.current) return;
 
     const canvas = canvasRef.current;
     const ctx = canvas.getContext('2d');
@@ -387,8 +387,6 @@ export function Track({
         className="flex-1 relative bg-slate-900 border-b border-border cursor-pointer"
         onClick={onSelect}
       >
-        {!track.collapsed && (
-          <>
         {track.audioBuffer ? (
           <canvas
             ref={canvasRef}
@@ -396,6 +394,7 @@ export function Track({
             onClick={handleCanvasClick}
           />
         ) : (
+          !track.collapsed && (
             <>
               <div
                 className={cn(
@@ -422,8 +421,7 @@ export function Track({
                 className="hidden"
               />
             </>
-            )}
+          )
-          </>
         )}
       </div>
     </div>