feat(quick-009): add VideoFrameGrabNode UI component

- Video input handle (left, purple) and image output handle (right, blue)
- First/Last frame position toggle with output clearing on toggle change
- Extract Frame button triggers regenerateNode
- Image preview area with clear button overlay
- Processing spinner overlay and error display
- BaseNode wrapper with title, comment, and keyboard run support

src/components/nodes/VideoFrameGrabNode.tsx

@@ -0,0 +1,175 @@
+"use client";
+
+import React, { useMemo } from "react";
+import { Handle, Position, NodeProps, Node } from "@xyflow/react";
+import { BaseNode } from "./BaseNode";
+import { useCommentNavigation } from "@/hooks/useCommentNavigation";
+import { useWorkflowStore } from "@/store/workflowStore";
+import { VideoFrameGrabNodeData } from "@/types";
+
+type VideoFrameGrabNodeType = Node<VideoFrameGrabNodeData, "videoFrameGrab">;
+
+export function VideoFrameGrabNode({ id, data, selected }: NodeProps<VideoFrameGrabNodeType>) {
+  const nodeData = data;
+  const commentNavigation = useCommentNavigation(id);
+  const updateNodeData = useWorkflowStore((state) => state.updateNodeData);
+  const regenerateNode = useWorkflowStore((state) => state.regenerateNode);
+  const isRunning = useWorkflowStore((state) => state.isRunning);
+  const edges = useWorkflowStore((state) => state.edges);
+  const nodes = useWorkflowStore((state) => state.nodes);
+
+  // Find connected source video from incoming edges
+  const sourceVideoUrl = useMemo(() => {
+    const incomingEdge = edges.find((e) => e.target === id && e.targetHandle === "video");
+    if (!incomingEdge) return null;
+
+    const sourceNode = nodes.find((n) => n.id === incomingEdge.source);
+    if (!sourceNode) return null;
+
+    const d = sourceNode.data as Record<string, unknown>;
+    return (d.outputVideo as string | null) ?? null;
+  }, [edges, nodes, id]);
+
+  const hasSourceVideo = Boolean(sourceVideoUrl);
+  const canExtract = hasSourceVideo && nodeData.status !== "loading" && !isRunning;
+
+  const handleExtract = () => {
+    regenerateNode(id);
+  };
+
+  return (
+    <BaseNode
+      id={id}
+      title="Frame Grab"
+      customTitle={nodeData.customTitle}
+      comment={nodeData.comment}
+      onCustomTitleChange={(title) => updateNodeData(id, { customTitle: title || undefined })}
+      onCommentChange={(comment) => updateNodeData(id, { comment: comment || undefined })}
+      onRun={canExtract ? handleExtract : undefined}
+      selected={selected}
+      isExecuting={isRunning}
+      hasError={nodeData.status === "error"}
+      commentNavigation={commentNavigation ?? undefined}
+      minWidth={320}
+      minHeight={320}
+    >
+      {/* Video In (target, left, 50%) */}
+      <Handle
+        type="target"
+        position={Position.Left}
+        id="video"
+        data-handletype="video"
+        isConnectable={true}
+        style={{ top: "50%" }}
+      />
+      <div
+        className="absolute text-[10px] font-medium whitespace-nowrap pointer-events-none text-right"
+        style={{ right: "calc(100% + 8px)", top: "calc(50% - 7px)", color: "rgb(168, 85, 247)" }}
+      >
+        Video In
+      </div>
+
+      {/* Image Out (source, right, 50%) */}
+      <Handle
+        type="source"
+        position={Position.Right}
+        id="image"
+        data-handletype="image"
+        isConnectable={true}
+        style={{ top: "50%" }}
+      />
+      <div
+        className="absolute text-[10px] font-medium whitespace-nowrap pointer-events-none"
+        style={{ left: "calc(100% + 8px)", top: "calc(50% - 7px)", color: "rgb(59, 130, 246)" }}
+      >
+        Image Out
+      </div>
+
+      <div className="flex-1 flex flex-col min-h-0 gap-2">
+        {/* Image preview area */}
+        <div className="flex-1 min-h-0 relative">
+          {nodeData.outputImage ? (
+            <>
+              <img
+                src={nodeData.outputImage}
+                className="absolute inset-0 w-full h-full object-contain rounded"
+                alt="Extracted frame"
+              />
+              {/* Clear output button */}
+              <button
+                onClick={() => updateNodeData(id, { outputImage: null, status: "idle" })}
+                className="absolute top-1 right-1 w-5 h-5 bg-neutral-900/80 hover:bg-red-600/80 rounded flex items-center justify-center text-neutral-400 hover:text-white transition-colors"
+                title="Clear extracted frame"
+              >
+                <svg className="w-3 h-3" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                  <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
+                </svg>
+              </button>
+            </>
+          ) : (
+            <div className="absolute inset-0 flex items-center justify-center border border-dashed border-neutral-600 rounded">
+              <span className="text-[10px] text-neutral-500 text-center px-4">
+                Connect a video and extract a frame
+              </span>
+            </div>
+          )}
+        </div>
+
+        {/* Frame position toggle (only when source video connected) */}
+        {hasSourceVideo && (
+          <div className="nodrag nowheel shrink-0 flex gap-1 px-1">
+            <button
+              onClick={() => updateNodeData(id, { framePosition: "first", outputImage: null })}
+              className={`flex-1 px-2 py-1 rounded text-xs font-medium transition-colors ${
+                nodeData.framePosition === "first"
+                  ? "bg-blue-600 text-white"
+                  : "bg-neutral-800 text-neutral-400 hover:text-neutral-200"
+              }`}
+            >
+              First
+            </button>
+            <button
+              onClick={() => updateNodeData(id, { framePosition: "last", outputImage: null })}
+              className={`flex-1 px-2 py-1 rounded text-xs font-medium transition-colors ${
+                nodeData.framePosition === "last"
+                  ? "bg-blue-600 text-white"
+                  : "bg-neutral-800 text-neutral-400 hover:text-neutral-200"
+              }`}
+            >
+              Last
+            </button>
+          </div>
+        )}
+
+        {/* Extract Frame button */}
+        <div className="shrink-0 flex justify-end px-1">
+          <button
+            onClick={handleExtract}
+            disabled={!canExtract}
+            className="px-3 py-1.5 bg-blue-600 hover:bg-blue-500 disabled:bg-neutral-700 disabled:text-neutral-500 disabled:cursor-not-allowed rounded text-white text-xs font-medium transition-colors"
+          >
+            {nodeData.status === "loading" ? "Extracting..." : "Extract Frame"}
+          </button>
+        </div>
+
+        {/* Processing overlay */}
+        {nodeData.status === "loading" && (
+          <div className="absolute inset-0 bg-neutral-900/70 rounded flex flex-col items-center justify-center gap-2">
+            <svg className="w-6 h-6 animate-spin text-white" fill="none" viewBox="0 0 24 24">
+              <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="3" />
+              <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z" />
+            </svg>
+            <span className="text-white text-xs">Extracting frame...</span>
+          </div>
+        )}
+
+        {/* Error display */}
+        {nodeData.status === "error" && nodeData.error && (
+          <div className="shrink-0 px-2 py-1.5 bg-red-900/30 border border-red-700/50 rounded">
+            <p className="text-[10px] text-red-400 break-words">{nodeData.error}</p>
+          </div>
+        )}
+      </div>
+    </BaseNode>
+  );
+}