fix(canvas): use server video duration options

tests/unit/image-canvas-page.test.tsx

@@ -510,7 +510,7 @@ describe('ImageCanvas Workspace-first design experience', () => {
     expect(screen.getByRole('button', { name: '确认并开始生成' })).toBeEnabled();
   });
 
-  it('limits legacy video durations to 2-6 seconds and preserves 6 seconds through confirmation', async () => {
+  it('uses server-provided video durations and preserves the selected value through confirmation', async () => {
     const videoConversation = conversationFixture();
     const videoQuote = videoConversation.messages[1].generationQuote!;
     videoConversation.brief.medium = 'video';
@@ -543,7 +543,7 @@ describe('ImageCanvas Workspace-first design experience', () => {
     const durationSelect = await screen.findByTestId('design-quote-duration');
     expect(durationSelect).toHaveValue('');
     expect(within(durationSelect).getAllByRole('option').map((option) => option.getAttribute('value')))
-      .toEqual(['', '2', '6']);
+      .toEqual(['', '2', '6', '7', '15']);
     expect(screen.getByRole('button', { name: '确认并开始生成' })).toBeDisabled();
 
     fireEvent.change(screen.getByLabelText('设计需求'), {
@@ -552,9 +552,9 @@ describe('ImageCanvas Workspace-first design experience', () => {
     fireEvent.click(screen.getByRole('button', { name: '发送给设计 Agent' }));
 
     expect(confirmImageWorkspaceGenerationMock).not.toHaveBeenCalled();
-    expect(await screen.findByRole('alert')).toHaveTextContent('请选择 2 至 6 秒的视频时长');
+    expect(await screen.findByRole('alert')).toHaveTextContent('请选择服务端提供的视频时长');
 
-    fireEvent.change(durationSelect, { target: { value: '6' } });
+    fireEvent.change(durationSelect, { target: { value: '15' } });
 
     await waitFor(() => expect(updateImageWorkspaceGenerationQuoteMock).toHaveBeenCalledWith(
       'workspace-cloud',
@@ -562,10 +562,10 @@ describe('ImageCanvas Workspace-first design experience', () => {
       videoQuote.finalPrompt,
       {
         ...videoQuote.generationParameters,
-        durationSeconds: 6,
+        durationSeconds: 15,
       },
     ));
-    await waitFor(() => expect(screen.getByTestId('design-quote-duration')).toHaveValue('6'));
+    await waitFor(() => expect(screen.getByTestId('design-quote-duration')).toHaveValue('15'));
     fireEvent.click(screen.getByRole('button', { name: '确认并开始生成' }));
 
     await waitFor(() => expect(confirmImageWorkspaceGenerationMock).toHaveBeenCalledWith(
@@ -577,7 +577,7 @@ describe('ImageCanvas Workspace-first design experience', () => {
       videoQuote.finalPrompt,
       {
         ...videoQuote.generationParameters,
-        durationSeconds: 6,
+        durationSeconds: 15,
       },
     ));
   });