fix: resolve CouchDB connection issues in backend tests

- Add jest.preSetup.js to mock modules before loading
- Skip CouchDB initialization during test environment
- Update browserslist data to fix deprecation warnings
- Improve error handling test infrastructure
- Fix fs.F_OK deprecation warning via dependency update

🤖 Generated with [AI Assistant]

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

backend/__tests__/jest.setup.js

@@ -1,40 +1,34 @@
-// Mock CouchDB service globally for all tests
-const mockCouchdbService = {
-  initialize: jest.fn().mockResolvedValue(true),
-  isReady: jest.fn().mockReturnValue(true),
-  isConnected: true,
-  isConnecting: false,
-  create: jest.fn(),
-  getById: jest.fn(),
-  get: jest.fn(),
-  find: jest.fn(),
-  destroy: jest.fn(),
-  delete: jest.fn(),
-  createDocument: jest.fn().mockImplementation((doc) => Promise.resolve({
-    _id: `test_${Date.now()}`,
-    _rev: '1-test',
-    ...doc
-  })),
-  updateDocument: jest.fn().mockImplementation((id, doc) => Promise.resolve({
-    _id: id,
-    _rev: '2-test',
-    ...doc
-  })),
-  deleteDocument: jest.fn().mockResolvedValue(true),
-  findByType: jest.fn().mockResolvedValue([]),
-  findUserById: jest.fn(),
-  findUserByEmail: jest.fn(),
-  update: jest.fn(),
-  updateUserPoints: jest.fn(),
-  getDocument: jest.fn(),
-  findDocumentById: jest.fn(),
-  bulkDocs: jest.fn(),
-  shutdown: jest.fn().mockResolvedValue(true),
-};
+// Get reference to the mocked couchdbService for test usage
+const couchdbService = require('../services/couchdbService');
 
-jest.mock('../services/couchdbService', () => mockCouchdbService);
+// Make mock available for tests to reference
+global.mockCouchdbService = couchdbService;
 
-// Make the mock available for tests to reference
+// Mock Cloudinary
+jest.mock('cloudinary', () => ({
+  v2: {
+    config: jest.fn(),
+    uploader: {
+      upload: jest.fn().mockResolvedValue({
+        secure_url: 'https://cloudinary.com/test/image.jpg',
+        public_id: 'test_public_id',
+        width: 500,
+        height: 500,
+        format: 'jpg'
+      }),
+      destroy: jest.fn().mockResolvedValue({ result: 'ok' })
+    }
+  }
+}));
+
+// Mock nodemailer
+jest.mock('nodemailer', () => ({
+  createTransport: jest.fn().mockReturnValue({
+    sendMail: jest.fn().mockResolvedValue({ messageId: 'test-message-id' })
+  })
+}));
+
+// Make mock available for tests to reference
 global.mockCouchdbService = mockCouchdbService;
 
 // Set test environment variables