T19: Fix useState type in SidePanel.tsx (use unknown[] for layers)

frontend/src/components/SidePanel.tsx

@@ -11,7 +11,7 @@ interface SidePanelProps {
 
 const SidePanel: React.FC<SidePanelProps> = ({ canvasRef, yjsDoc }) => {
   const [activeTab, setActiveTab] = useState('blocks');
-  const [layers, setLayers] = useState<Record<string, unknown> & { id: string }[]>([]);
+  const [layers, setLayers] = useState<unknown[]>([]);
   const [activeLayer, setActiveLayer] = useState('');
   const localCanvasRef = useRef(null);
   const localYjsDocRef = useRef(null);