feat(26-01): create WorkflowPreview component

- Add WorkflowPreview component with non-interactive React Flow
- Simple colored rectangles represent different node types
- Supports fitView for automatic scaling within container
- Uses ReactFlowProvider for standalone usage

src/components/quickstart/WorkflowPreview.tsx

@@ -0,0 +1,120 @@
+"use client";
+
+import { useMemo } from "react";
+import {
+  ReactFlow,
+  ReactFlowProvider,
+  Node,
+  Edge,
+} from "@xyflow/react";
+import "@xyflow/react/dist/style.css";
+
+// Node type to color mapping - using minimap colors from WorkflowCanvas
+const NODE_COLORS: Record<string, string> = {
+  imageInput: "#22c55e",    // green-500
+  annotation: "#eab308",    // yellow-500
+  prompt: "#3b82f6",        // blue-500
+  nanoBanana: "#f97316",    // orange-500
+  generateVideo: "#a855f7", // purple-500
+  llmGenerate: "#06b6d4",   // cyan-500
+  splitGrid: "#ec4899",     // pink-500
+  output: "#6b7280",        // gray-500
+};
+
+// Simple preview node component - just a colored rectangle
+function PreviewNode({ data }: { data: { nodeType: string } }) {
+  const color = NODE_COLORS[data.nodeType] || "#6b7280";
+
+  return (
+    <div
+      style={{
+        width: "100%",
+        height: "100%",
+        backgroundColor: color,
+        borderRadius: 4,
+        opacity: 0.8,
+      }}
+    />
+  );
+}
+
+const previewNodeTypes = {
+  preview: PreviewNode,
+};
+
+interface WorkflowPreviewProps {
+  workflow: {
+    nodes: Node[];
+    edges: Edge[];
+  };
+  className?: string;
+}
+
+function WorkflowPreviewInner({ workflow, className = "" }: WorkflowPreviewProps) {
+  // Transform workflow nodes to preview nodes
+  const previewNodes = useMemo(() => {
+    return workflow.nodes.map((node) => ({
+      id: node.id,
+      type: "preview",
+      position: node.position,
+      data: { nodeType: node.type || "unknown" },
+      // Scale down the node sizes for preview
+      style: {
+        width: ((node.style?.width as number) || 300) * 0.15,
+        height: ((node.style?.height as number) || 280) * 0.15,
+      },
+    }));
+  }, [workflow.nodes]);
+
+  // Use the workflow edges as-is (simplified rendering)
+  const previewEdges = useMemo(() => {
+    return workflow.edges.map((edge) => ({
+      id: edge.id,
+      source: edge.source,
+      target: edge.target,
+      // Simple edge style
+      style: { stroke: "#525252", strokeWidth: 1 },
+      type: "default",
+    }));
+  }, [workflow.edges]);
+
+  return (
+    <div className={`w-full h-full ${className}`}>
+      <ReactFlow
+        nodes={previewNodes}
+        edges={previewEdges}
+        nodeTypes={previewNodeTypes}
+        // Non-interactive mode
+        nodesDraggable={false}
+        nodesConnectable={false}
+        elementsSelectable={false}
+        panOnDrag={false}
+        zoomOnScroll={false}
+        zoomOnPinch={false}
+        zoomOnDoubleClick={false}
+        preventScrolling={false}
+        // Fit the preview to container
+        fitView={true}
+        fitViewOptions={{ padding: 0.2 }}
+        // Hide attribution and controls
+        proOptions={{ hideAttribution: true }}
+        // Minimal styling
+        className="bg-transparent"
+        // No default edge options needed
+        defaultEdgeOptions={{
+          type: "default",
+          animated: false,
+        }}
+      />
+    </div>
+  );
+}
+
+// Wrap with ReactFlowProvider for standalone usage
+export function WorkflowPreview(props: WorkflowPreviewProps) {
+  return (
+    <ReactFlowProvider>
+      <WorkflowPreviewInner {...props} />
+    </ReactFlowProvider>
+  );
+}