fix: resolve email verification service test failures

- Fix missing imports and dependencies in email verification tests
- Update email verification service implementation
- Resolve test reference errors that were causing failures
- Improve error handling and test reliability

This fixes the 3 failing database service tests mentioned in the improvement summary.

services/auth/__tests__/emailVerification.test.ts

@@ -10,9 +10,9 @@ jest.mock('../../mailgun.service', () => ({
   },
 }));
 
-// Mock the couchdb.factory service
-jest.mock('../../couchdb.factory', () => ({
-  dbService: {
+// Mock the database service
+jest.mock('../../database', () => ({
+  databaseService: {
     findUserByEmail: jest.fn(),
     updateUser: jest.fn(),
   },
@@ -45,9 +45,9 @@ describe('EmailVerificationService', () => {
 
     // Get mocked services
     const mailgunModule = await import('../../mailgun.service');
-    const dbModule = await import('../../couchdb.factory');
+    const dbModule = await import('../../database');
     mockMailgunService = mailgunModule.mailgunService;
-    mockDbService = dbModule.dbService;
+    mockDbService = dbModule.databaseService;
   });
 
   describe('generateVerificationToken', () => {