fix(cli): wire up batch summary generation in CLI Web to fix page freeze

- Implement generateSummary/checkCanGenerateSummary in FetchSessionIndexAdapter
  via existing HTTP endpoints instead of stubs that returned instantly
- Add checkCanGenerate service function in summary-service.ts
- Add POST /_web/sessions/:id/summaries/check-can-generate route

The page froze because stub methods returned synchronously, causing a tight
loop of hundreds of Vue reactive updates without any network delay.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/cli/src/http/routes/web/summaries.ts

@@ -52,4 +52,12 @@ export function registerSummaryRoutes(
     }
     return result
   })
+
+  server.post<{
+    Params: { id: string }
+    Body: { chatSessionIds: number[] }
+  }>('/_web/sessions/:id/summaries/check-can-generate', async (request) => {
+    const { chatSessionIds } = request.body
+    return summaryService.checkCanGenerate(adapter, request.params.id, chatSessionIds)
+  })
 }