重构画布动作上下文与刷新链路

新增编辑器级画布动作上下文与 Provider，统一承载画布动作
将 Agent 对话和任务侧栏的画布刷新迁移到上下文，移除逐层回调透传
统一生成任务完成后的项目刷新入口，避免重复加载项目快照
补齐上下文及刷新链路测试，并更新测试 Provider 装配

src/components/image-editor/ImageCanvasTaskSidebarView.tsx

@@ -17,6 +17,7 @@ import {
 
 import type { ExternalGenerationTaskRecord } from '../../../packages/shared/src/contracts/externalGeneration';
 import { listExternalGenerationTasks } from '../../services/external-generation';
+import { useImageCanvasActions } from './ImageCanvasActionsContext.ts';
 import { EditorIconButton } from './ImageCanvasEditorPrimitives';
 import type { CanvasTaskStatus } from './ImageCanvasEditorTypes';
 import { useImageCanvasContextStore } from './useImageCanvasContextStore.ts';
@@ -280,6 +281,7 @@ export function ImageCanvasTaskSidebarView({
   onFocusExternalTask,
   onExternalTasksCompleted,
 }: ImageCanvasTaskSidebarViewProps) {
+  const { refreshCanvas } = useImageCanvasActions();
   const projectId = useImageCanvasContextStore((state) => state.projectId);
   const normalizedProjectId = projectId?.trim() ?? '';
   const [activeTab, setActiveTab] = useState<TaskSidebarTab>('active');
@@ -334,9 +336,10 @@ export function ImageCanvasTaskSidebarView({
       for (const task of newlyCompletedTasks) {
         completedRefreshNotifiedTaskIdsRef.current.add(task.jobId);
       }
+      refreshCanvas();
       onExternalTasksCompleted?.(newlyCompletedTasks);
     },
-    [onExternalTasksCompleted],
+    [onExternalTasksCompleted, refreshCanvas],
   );
 
   useEffect(() => {