Initial commit: Pixel AI comic/video creation platform

- FastAPI backend with SQLModel, Alembic migrations, AgentScope agents
- Next.js 15 frontend with React 19, Tailwind, Zustand, React Flow
- Multi-provider AI system (DashScope, Kling, MiniMax, Volcengine, OpenAI, etc.)
- All HTTP clients migrated from sync requests to async httpx
- Admin-managed API keys via environment variables
- SSRF vulnerability fixed in ensure_url()

frontend/src/components/canvas/commands/UpdateNodeCommand.ts

@@ -0,0 +1,57 @@
+import { Command } from './Command';
+import { AppNodeType, AppNodeData } from '../types/node';
+
+/**
+ * Command to update a node's data
+ */
+export class UpdateNodeCommand implements Command {
+    private nodeId: string;
+    private oldData: Partial<AppNodeData>;
+    private newData: Partial<AppNodeData>;
+    private setNodes: (updater: (nodes: AppNodeType[]) => AppNodeType[]) => void;
+    private getNodes: () => AppNodeType[];
+
+    constructor(
+        nodeId: string,
+        newData: Partial<AppNodeData>,
+        setNodes: (updater: (nodes: AppNodeType[]) => AppNodeType[]) => void,
+        getNodes: () => AppNodeType[]
+    ) {
+        this.nodeId = nodeId;
+        this.newData = newData;
+        this.setNodes = setNodes;
+        this.getNodes = getNodes;
+        
+        // Store old data for undo
+        const node = getNodes().find(n => n.id === nodeId);
+        if (node && node.type === 'appNode') {
+            this.oldData = { ...node.data };
+        } else {
+            this.oldData = {};
+        }
+    }
+
+    execute(): void {
+        this.setNodes((nodes) => 
+            nodes.map(n => 
+                n.id === this.nodeId && n.type === 'appNode'
+                    ? { ...n, data: { ...n.data, ...this.newData } }
+                    : n
+            )
+        );
+    }
+
+    undo(): void {
+        this.setNodes((nodes) => 
+            nodes.map(n => 
+                n.id === this.nodeId && n.type === 'appNode'
+                    ? { ...n, data: { ...n.data, ...this.oldData } }
+                    : n
+            )
+        );
+    }
+
+    getDescription(): string {
+        return `Update node: ${this.nodeId}`;
+    }
+}