修复图集快速编辑后端校验与错误提示

后端允许完整图标图集进入图片快速编辑，仅继续禁止单个图标。

快速编辑失败时向红色错误框传递具体错误文案。

补充前后端回归测试并同步画布编辑器技术文档。

src/components/image-editor/ImageCanvasQuickEditPanelView.test.tsx

@@ -124,6 +124,27 @@ describe('ImageCanvasQuickEditPanelView', () => {
     expect(rememberImageModel).toHaveBeenCalledWith('gpt-image-2');
   });
 
+  it('renders the failure message inside the quick edit alert', () => {
+    render(
+      <QuickEditPanelHarness
+        initialPanel={{
+          sourceLayerId: 'layer-a',
+          prompt: '调整图集布局',
+          size: '1024x1024',
+          aspectRatio: '1:1',
+          imageSize: '1K',
+          model: 'gpt-image-2',
+          status: 'failed',
+          errorMessage: '图集快速编辑失败',
+        }}
+      />,
+    );
+
+    expect(screen.getByRole('alert').textContent).toContain(
+      '图集快速编辑失败',
+    );
+  });
+
   it('submits without rendering a standalone close button', () => {
     const submitQuickEdit = vi.fn();
     render(

src/components/image-editor/ImageCanvasQuickEditPanelView.tsx

@@ -53,6 +53,7 @@ function createQuickEditDialog(
     mode: isQuickEdit ? 'quick-edit' : 'generate',
     prompt: panel.prompt,
     status: panel.status,
+    errorMessage: panel.errorMessage,
     sourceLayerId: panel.sourceLayerId,
     generationReferences: panel.quickEditReferences,
     assetLabel: panel.assetLabel,