fix: address review followups

src/web/pages/DownstreamKeys.test.tsx

@@ -193,7 +193,7 @@ describe('DownstreamKeys page', () => {
       expect(text).toContain('主分组');
       expect(text).toContain('移动端');
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 
@@ -447,7 +447,7 @@ describe('DownstreamKeys page', () => {
       expect(collectText(root!.root)).not.toContain('固定窗口对比');
       expect(collectText(root!.root)).not.toContain('trend:2');
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 

src/web/pages/accounts.create-intent.test.tsx

@@ -64,7 +64,7 @@ describe('Accounts create intent handling', () => {
       const selects = root.root.findAllByType(ModernSelect);
       expect(selects[1]?.props.value).toBe('10');
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 
@@ -77,7 +77,7 @@ describe('Accounts create intent handling', () => {
       const selects = root.root.findAllByType(ModernSelect);
       expect(selects[1]?.props.value).toBe('10');
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 
@@ -88,7 +88,7 @@ describe('Accounts create intent handling', () => {
       expect(rendered).not.toContain('添加 Session 连接');
       expect(rendered).not.toContain('添加 API Key 连接');
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 });

src/web/pages/sites.disabled-models-save.test.tsx

@@ -146,7 +146,7 @@ describe('Sites disabled models save', () => {
 
       expect(apiMock.updateSiteDisabledModels).toHaveBeenCalledWith(1, ['gpt-4o']);
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 
@@ -190,7 +190,7 @@ describe('Sites disabled models save', () => {
 
       expect(apiMock.updateSiteDisabledModels).toHaveBeenCalledWith(1, ['gpt-4o']);
     } finally {
-      root.unmount();
+      root?.unmount();
     }
   });
 });