feat: implement Convex-synced canvas foundation

components/canvas/nodes/note-node.tsx

@@ -0,0 +1,20 @@
+"use client";
+
+import { type Node, type NodeProps } from "@xyflow/react";
+
+import BaseNodeWrapper from "./base-node-wrapper";
+
+export type NoteNodeData = {
+  content?: string;
+};
+
+export type NoteNode = Node<NoteNodeData, "note">;
+
+export default function NoteNode({ data, selected }: NodeProps<NoteNode>) {
+  return (
+    <BaseNodeWrapper selected={selected} className="w-52 p-3">
+      <div className="mb-1 text-xs font-medium text-muted-foreground">Notiz</div>
+      <p className="whitespace-pre-wrap text-sm">{data.content || "Leere Notiz"}</p>
+    </BaseNodeWrapper>
+  );
+}