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/emailVerification.service.ts

@@ -2,7 +2,7 @@ import { v4 as uuidv4 } from 'uuid';
 import { EmailVerificationToken, AuthenticatedUser } from './auth.types';
 import { mailgunService } from '../mailgun.service';
 import { AccountStatus } from './auth.constants';
-import { dbService } from '../couchdb.factory';
+import { databaseService } from '../database';
 
 const TOKEN_EXPIRY_HOURS = 24;
 
@@ -63,7 +63,7 @@ export class EmailVerificationService {
     }
 
     // Find the user (in production, this would be a proper database lookup)
-    const user = await dbService.findUserByEmail(verificationToken.email);
+    const user = await databaseService.findUserByEmail(verificationToken.email);
 
     return user as AuthenticatedUser;
   }
@@ -76,7 +76,7 @@ export class EmailVerificationService {
       status: AccountStatus.ACTIVE,
     };
 
-    await dbService.updateUser(updatedUser);
+    await databaseService.updateUser(updatedUser);
 
     // Remove used token
     const tokens = JSON.parse(