feat: implement Convex-synced canvas foundation

components/canvas/nodes/group-node.tsx

@@ -0,0 +1,15 @@
+"use client";
+
+import { type Node, type NodeProps } from "@xyflow/react";
+
+import BaseNodeWrapper from "./base-node-wrapper";
+
+export type GroupNode = Node<{ label?: string }, "group">;
+
+export default function GroupNode({ data, selected }: NodeProps<GroupNode>) {
+  return (
+    <BaseNodeWrapper selected={selected} className="min-h-[150px] min-w-[200px] border-dashed p-3">
+      <div className="text-xs font-medium text-muted-foreground">{data.label || "Gruppe"}</div>
+    </BaseNodeWrapper>
+  );
+}