修复画布提示与图片尺寸一致性

提示弹窗三秒后自动消失并保留手动关闭
统一 nanobanana2 与 gpt-image-2 同规格图片的交付像素
补充尺寸归一和提示生命周期回归测试
同步图片画布生成契约文档

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

@@ -1417,7 +1417,7 @@ describe('useImageCanvasGenerationWorkflow', () => {
     expect(screen.getByTestId('reference-pick-warning').textContent).toBe('-');
   });
 
-  it('keeps reference pick warnings visible until the user takes a follow-up action', () => {
+  it('dismisses reference pick warnings after three seconds', () => {
     vi.useFakeTimers();
     try {
       render(<GenerationWorkflowHarness />);
@@ -1430,12 +1430,18 @@ describe('useImageCanvasGenerationWorkflow', () => {
       );
 
       act(() => {
-        vi.advanceTimersByTime(10_000);
+        vi.advanceTimersByTime(2_999);
       });
 
       expect(screen.getByTestId('reference-pick-warning').textContent).toBe(
         '选择的图片不是角色规范图，请选择生成规范里的角色规范。',
       );
+
+      act(() => {
+        vi.advanceTimersByTime(1);
+      });
+
+      expect(screen.getByTestId('reference-pick-warning').textContent).toBe('-');
     } finally {
       vi.useRealTimers();
     }

src/components/image-editor/useImageCanvasGenerationWorkflow.ts

@@ -720,6 +720,20 @@ export function useImageCanvasGenerationWorkflow({
   const [generationWarning, setGenerationWarning] = useState<string | null>(
     null,
   );
+
+  useEffect(() => {
+    if (!generationWarning) {
+      return;
+    }
+
+    const timer = window.setTimeout(() => {
+      setGenerationWarning(null);
+    }, 3_000);
+
+    return () => {
+      window.clearTimeout(timer);
+    };
+  }, [generationWarning]);
   const [cropExpandPanel, setCropExpandPanel] =
     useState<CropExpandPanelState | null>(null);
   const [uiAssetExtractionState, setUiAssetExtractionState] =