fix: convert selectedTrack.name to string in Effect Chain header

Fixed [object Object] display in Effect Chain section of SidePanel
by adding String() conversion to selectedTrack.name.

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

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

components/layout/SidePanel.tsx

@@ -300,7 +300,7 @@ export function SidePanel({
               <h3 className="text-xs font-semibold text-muted-foreground uppercase">
                 Effect Chain
                 {selectedTrack && (
-                  <span className="text-primary ml-2">({selectedTrack.name})</span>
+                  <span className="text-primary ml-2">({String(selectedTrack.name || 'Untitled Track')})</span>
                 )}
               </h3>
               <div className="flex gap-1">