fix: EmailManager route calls get_email_users not get_users

The method is named get_email_users in EmailManager; the route was
calling the non-existent get_users, causing an AttributeError on every
GET /api/email/users request.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_api_endpoints.py

@@ -398,7 +398,7 @@ class TestAPIEndpoints(unittest.TestCase):
     def test_email_endpoints(self, mock_email, mock_sr):
         mock_sr.get.return_value = {'id': 'email', 'installed': True}
         # Ensure all relevant mock methods return JSON-serializable values
-        mock_email.get_users.return_value = [{'username': 'user1', 'domain': 'cell', 'email': 'user1@cell'}]
+        mock_email.get_email_users.return_value = [{'username': 'user1', 'domain': 'cell', 'email': 'user1@cell'}]
         mock_email.create_email_user.return_value = True
         mock_email.delete_email_user.return_value = True
         mock_email.get_status.return_value = {'postfix_running': True, 'dovecot_running': True, 'total_users': 1, 'total_size_bytes': 0, 'total_size_mb': 0.0, 'users': [{'username': 'user1', 'domain': 'cell', 'email': 'user1@cell'}]}
@@ -409,10 +409,10 @@ class TestAPIEndpoints(unittest.TestCase):
         response = self.client.get('/api/email/users')
         self.assertEqual(response.status_code, 200)
         self.assertIsInstance(json.loads(response.data), list)
-        mock_email.get_users.side_effect = Exception('fail')
+        mock_email.get_email_users.side_effect = Exception('fail')
         response = self.client.get('/api/email/users')
         self.assertEqual(response.status_code, 500)
-        mock_email.get_users.side_effect = None
+        mock_email.get_email_users.side_effect = None
         # /api/email/users (POST)
         response = self.client.post('/api/email/users', data=json.dumps({'username': 'user1', 'domain': 'cell', 'password': 'pw'}), content_type='application/json')
         self.assertEqual(response.status_code, 200)