修复画布Agent聊天生成体验

让画布 Agent 消息统一走后端规划与 LLM 回复
修复生成图片在聊天、画布和素材库中的展示与恢复
补齐右键删除、画布焦点、聊天滚轮和面板避让交互
同步 Agent 事件契约、文档和定向回归测试

src/components/image-editor/ImageCanvasLayerCommandModel.ts

@@ -3,6 +3,7 @@ import type {
   CanvasContextMenuState,
   CanvasLayer,
 } from './ImageCanvasEditorTypes';
+import { getCanvasGenerationSelectionId } from './ImageCanvasSelectionModel';
 
 export type CanvasLayerMoveMode = 'up' | 'down' | 'top' | 'bottom';
 
@@ -31,12 +32,14 @@ export function resolveContextTargetLayerIds(
   menu: CanvasContextMenuState | null,
   selectedLayerIds: string[],
 ) {
-  if (menu?.kind !== 'layer') {
+  if (!menu || menu.kind === 'blank') {
     return [];
   }
-  return selectedLayerIds.includes(menu.layerId)
-    ? [...selectedLayerIds]
-    : [menu.layerId];
+  const targetId =
+    menu.kind === 'generation-dialog'
+      ? getCanvasGenerationSelectionId(menu.dialogId)
+      : menu.layerId;
+  return selectedLayerIds.includes(targetId) ? [...selectedLayerIds] : [targetId];
 }
 
 export function getCanvasLayersByIds(