fix: resolve TypeScript build errors in test files

- Remove unused React imports in AgentStatusIndicator and WebSocketIndicator tests
- Fix Response type cast in api-helpers test (as unknown as Response)

web/src/__tests__/AgentStatusIndicator.test.tsx

@@ -1,7 +1,6 @@
 /**
  * Tests for components/shared/AgentStatusIndicator.tsx — agent status states.
  */
-import React from 'react';
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { render, screen, cleanup } from '@testing-library/react';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';

web/src/__tests__/WebSocketIndicator.test.tsx

@@ -1,7 +1,6 @@
 /**
  * Tests for components/shared/WebSocketIndicator.tsx — status indicator states.
  */
-import React from 'react';
 import { describe, it, expect, afterEach } from 'vitest';
 import { render, screen, cleanup } from '@testing-library/react';
 import { WebSocketStatusProvider } from '@/contexts/WebSocketContext';

web/src/__tests__/api-helpers.test.ts

@@ -11,7 +11,7 @@ function jsonResponse(body: unknown, status = 200): Response {
     ok: status >= 200 && status < 300,
     status,
     json: async () => body,
-  } as Response;
+  } as unknown as Response;
 }
 
 function brokenJsonResponse(status = 200): Response {
@@ -21,7 +21,7 @@ function brokenJsonResponse(status = 200): Response {
     json: async () => {
       throw new SyntaxError('Unexpected token');
     },
-  } as Response;
+  } as unknown as Response;
 }
 
 // ── Tests ────────────────────────────────────────────────────