完善遮罩删除范围选择

- 删除/清空已保存标注前预检后端 annotation id，跳过本地陈旧 id，避免重复 DELETE 产生 404 控制台红字

- 左侧工具栏新增 DEL 删除选中遮罩入口，调整清空遮罩弹窗文案为“清空所有传播帧”，并加入按帧范围选择入口

- 区域合并和重叠区域去除在存在传播帧时弹出当前帧/所有传播帧选择，传播帧同步后保留原 lineage metadata

- 多 polygon 或分离区域组成的 mask 选中后显示全部顶点与插点手柄，同帧传播链分散 mask 点选时联动高亮

- 调整工具栏分组分隔线位置，只在清空遮罩下方保留 tool-group-separator 测试标记

- 更新 VideoWorkspace、CanvasArea、ToolsPalette 回归测试和相关项目文档

src/components/CanvasArea.test.tsx

@@ -871,11 +871,12 @@ describe('CanvasArea', () => {
     fireEvent.click(paths[1]);
     const vertexHandles = screen.getAllByTestId('konva-circle')
       .filter((element) => element.getAttribute('data-fill') === '#ffffff');
+    expect(vertexHandles).toHaveLength(6);
     fireEvent.mouseUp(vertexHandles[0], { clientX: 120, clientY: 120 });
 
     expect(useStore.getState().masks[0].segmentation).toEqual([
-      [10, 10, 50, 10, 50, 40],
-      [120, 120, 150, 100, 150, 140],
+      [120, 120, 50, 10, 50, 40],
+      [100, 100, 150, 100, 150, 140],
     ]);
   });
 
@@ -979,6 +980,8 @@ describe('CanvasArea', () => {
     fireEvent.click(paths[0]);
     fireEvent.click(paths[1]);
     fireEvent.click(screen.getByRole('button', { name: '合并选中' }));
+    expect(screen.getByText('选择操作范围')).toBeInTheDocument();
+    fireEvent.click(screen.getByRole('button', { name: '处理所有传播帧' }));
 
     await waitFor(() => expect(onDeleteMaskAnnotations).toHaveBeenCalledWith(expect.arrayContaining(['2', '20'])));
     const masks = useStore.getState().masks;
@@ -1094,6 +1097,8 @@ describe('CanvasArea', () => {
     fireEvent.click(paths[0]);
     fireEvent.click(paths[1]);
     fireEvent.click(screen.getByRole('button', { name: '从主区域去除' }));
+    expect(screen.getByText('选择操作范围')).toBeInTheDocument();
+    fireEvent.click(screen.getByRole('button', { name: '处理所有传播帧' }));
 
     await waitFor(() => expect(useStore.getState().masks.find((mask) => mask.id === 'annotation-10')?.saveStatus).toBe('dirty'));
     expect(onDeleteMaskAnnotations).not.toHaveBeenCalled();