统一工作区清空遮罩入口

- 移除 Canvas 右下角旧清空遮罩和应用分类按钮，清空入口统一到左侧工具栏

- 清空遮罩优先作用于当前帧选中 mask，无选中时作用于当前帧全部 mask

- 目标 mask 无传播链结果时直接清当前帧，有传播链结果时弹窗选择只清当前帧、清空传播所有帧或取消

- 保留布尔工具右下角合并/去除操作区，避免旧分类按钮误改整帧

- 更新 Canvas、工具栏、工作区测试，覆盖直接清空、传播链范围选择和取消路径

- 同步更新前端审计、需求冻结、设计冻结、测试计划和 AGENTS 说明

src/components/CanvasArea.tsx

@@ -9,7 +9,6 @@ import type { Frame, Mask } from '../store/useStore';
 interface CanvasAreaProps {
   activeTool: string;
   frame: Frame | null;
-  onClearMasks?: () => void;
   onDeleteMaskAnnotations?: (annotationIds: string[]) => Promise<void> | void;
 }
 
@@ -417,7 +416,7 @@ function geometriesOverlap(first: MultiPolygon, second: MultiPolygon): boolean {
   return polygonClipping.intersection(first, second).length > 0;
 }
 
-export function CanvasArea({ activeTool, frame, onClearMasks, onDeleteMaskAnnotations }: CanvasAreaProps) {
+export function CanvasArea({ activeTool, frame, onDeleteMaskAnnotations }: CanvasAreaProps) {
   const containerRef = useRef<HTMLDivElement>(null);
   const [stageSize, setStageSize] = useState({ width: 800, height: 600 });
   const [scale, setScale] = useState(1);
@@ -448,7 +447,6 @@ export function CanvasArea({ activeTool, frame, onClearMasks, onDeleteMaskAnnota
   const masks = useStore((state) => state.masks);
   const addMask = useStore((state) => state.addMask);
   const updateMask = useStore((state) => state.updateMask);
-  const clearMasks = useStore((state) => state.clearMasks);
   const setMasks = useStore((state) => state.setMasks);
   const setGlobalSelectedMaskIds = useStore((state) => state.setSelectedMaskIds);
   const maskPreviewOpacity = useStore((state) => state.maskPreviewOpacity);
@@ -971,37 +969,6 @@ export function CanvasArea({ activeTool, frame, onClearMasks, onDeleteMaskAnnota
     }
   }, [activeClass, activeTemplateId, addMask, aiModel, frame?.height, frame?.id, frame?.width, image?.height, image?.naturalHeight, image?.naturalWidth, image?.width, masks, samCandidateMaskId, setMasks, updateMask]);
 
-  const handleApplyActiveClass = () => {
-    if (!frame?.id || !activeClass) return;
-    const seedIds = selectedMaskIds.length > 0
-      ? selectedMaskIds
-      : frameMasks.map((mask) => mask.id);
-    const targetIds = findPropagationChainMaskIds(seedIds, masks);
-    setMasks(masks.map((mask) => {
-      if (!targetIds.has(mask.id)) return mask;
-      return {
-        ...mask,
-        templateId: activeTemplateId || mask.templateId,
-        classId: activeClass.id,
-        className: activeClass.name,
-        classZIndex: activeClass.zIndex,
-        classMaskId: activeClass.maskId,
-        label: activeClass.name,
-        color: activeClass.color,
-        saveStatus: mask.annotationId ? 'dirty' : 'draft',
-        saved: Boolean(mask.annotationId) ? false : mask.saved,
-      };
-    }));
-  };
-
-  const handleClearMasks = () => {
-    if (onClearMasks) {
-      onClearMasks();
-      return;
-    }
-    clearMasks();
-  };
-
   const deleteMasksById = useCallback((maskIds: string[]) => {
     if (maskIds.length === 0) return;
     const idSet = expandedPropagationDeletionMaskIds(maskIds, masks);
@@ -1772,36 +1739,20 @@ export function CanvasArea({ activeTool, frame, onClearMasks, onDeleteMaskAnnota
           <span>待更新: {dirtyMaskCount}</span>
        </div>
 
-       {frameMasks.length > 0 && (
+       {frameMasks.length > 0 && isBooleanTool && (
          <div className="absolute bottom-4 right-4 flex gap-2">
-           {isBooleanTool && (
-             <div className="flex items-center gap-2">
-               <span className="text-xs bg-white/5 text-gray-300 border border-white/10 px-2.5 py-1.5 rounded">
-                 已选 {booleanSelectedMasks.length}
-               </span>
-               <button
-                 onClick={handleBooleanOperation}
-                 disabled={booleanSelectedMasks.length < 2}
-                 className="text-xs bg-emerald-500/10 hover:bg-emerald-500/20 text-emerald-300 border border-emerald-500/20 px-3 py-1.5 rounded transition-colors disabled:opacity-40 disabled:cursor-not-allowed disabled:hover:bg-emerald-500/10"
-               >
-                 {effectiveTool === 'area_merge' ? '合并选中' : '从主区域去除'}
-               </button>
-             </div>
-           )}
-           {activeClass && (
+           <div className="flex items-center gap-2">
+             <span className="text-xs bg-white/5 text-gray-300 border border-white/10 px-2.5 py-1.5 rounded">
+               已选 {booleanSelectedMasks.length}
+             </span>
              <button
-               onClick={handleApplyActiveClass}
-               className="text-xs bg-cyan-500/10 hover:bg-cyan-500/20 text-cyan-300 border border-cyan-500/20 px-3 py-1.5 rounded transition-colors"
+               onClick={handleBooleanOperation}
+               disabled={booleanSelectedMasks.length < 2}
+               className="text-xs bg-emerald-500/10 hover:bg-emerald-500/20 text-emerald-300 border border-emerald-500/20 px-3 py-1.5 rounded transition-colors disabled:opacity-40 disabled:cursor-not-allowed disabled:hover:bg-emerald-500/10"
              >
-               应用分类
+               {effectiveTool === 'area_merge' ? '合并选中' : '从主区域去除'}
              </button>
-           )}
-           <button
-             onClick={handleClearMasks}
-             className="text-xs bg-red-500/10 hover:bg-red-500/20 text-red-400 border border-red-500/20 px-3 py-1.5 rounded transition-colors"
-           >
-             清空遮罩
-           </button>
+           </div>
          </div>
        )}
     </div>