fix(studio): lock the canvas for scene-engine templates (no drag/resize)

For FLEXIBLE (Remotion / FlexStory) templates the render uses fixed positions —
dragging or resizing a layer on the Konva canvas does nothing to the output, which
is confusing. Make the canvas a read-only PREVIEW for those projects: the Konva
Layer is listening=false (no drag/select/transform), the Transformer is hidden, and
the auto-thumbnail capture is skipped so the flat Konva snapshot can't overwrite the
real rendered per-scene image. Editing happens only through the field form
(BlockFieldForm). AE/Konva templates are unchanged. Gated on isFlexStoryProject().

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/studio/CanvasEditor.tsx

@@ -14,7 +14,7 @@ import {
   resetNodeScale,
 } from "@/lib/canvas-transform";
 import { getShapeProps } from "@/lib/studio-layer-props";
-import { getActiveScene, useStudioStore } from "@/lib/studio-store";
+import { getActiveScene, isFlexStoryProject, useStudioStore } from "@/lib/studio-store";
 import type { Layer as StudioLayer } from "@/lib/studio-types";
 
 export const STAGE_WIDTH = 1280;
@@ -36,6 +36,12 @@ export function CanvasEditor() {
   const setSelectedLayer = useStudioStore((state) => state.setSelectedLayer);
   const updateLayer = useStudioStore((state) => state.updateLayer);
   const updateScene = useStudioStore((state) => state.updateScene);
+  // Scene-engine (FlexStory) templates render in Remotion at fixed positions —
+  // dragging/resizing layers on the canvas does nothing, so the canvas becomes a
+  // read-only preview; editing happens only via the field form.
+  const lockedGeometry = useStudioStore((state) =>
+    isFlexStoryProject(state.chooseMode)
+  );
 
   const thumbTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
@@ -90,9 +96,11 @@ export function CanvasEditor() {
     }
   }, [selectedLayerId, sortedLayers, isPlaying]);
 
-  // Auto-capture scene thumbnail whenever layers or background change
+  // Auto-capture scene thumbnail whenever layers or background change. Skipped for
+  // scene-engine templates so the flat Konva snapshot doesn't overwrite the real
+  // rendered per-scene image.
   useEffect(() => {
-    if (isPlaying || !activeSceneId) return;
+    if (isPlaying || !activeSceneId || lockedGeometry) return;
 
     if (thumbTimerRef.current) clearTimeout(thumbTimerRef.current);
     thumbTimerRef.current = setTimeout(() => {
@@ -182,9 +190,9 @@ export function CanvasEditor() {
         height={stageHeight}
         scaleX={scale}
         scaleY={scale}
-        onMouseDown={isPlaying ? undefined : handleStagePointerDown}
+        onMouseDown={isPlaying || lockedGeometry ? undefined : handleStagePointerDown}
       >
-        <Layer>
+        <Layer listening={!lockedGeometry}>
           <Rect
             name="background"
             x={0}
@@ -203,7 +211,7 @@ export function CanvasEditor() {
               registerNode={registerNode}
             />
           ))}
-          {!isPlaying ? (
+          {!isPlaying && !lockedGeometry ? (
             <Transformer
               ref={transformerRef}
               rotateEnabled