Allow login via email

src/main/java/com/openisle/controller/AuthController.java

@@ -69,6 +69,9 @@ public class AuthController {
             return ResponseEntity.badRequest().body(Map.of("error", "Invalid captcha"));
         }
         Optional<User> userOpt = userService.findByUsername(req.getUsernameOrEmail());
+        if (userOpt.isEmpty()) {
+            userOpt = userService.findByEmail(req.getUsernameOrEmail());
+        }
         if (userOpt.isEmpty() || !userService.matchesPassword(userOpt.get(), req.getPassword())) {
             return ResponseEntity.badRequest().body(Map.of(
                     "error", "Invalid credentials",

src/main/java/com/openisle/service/UserService.java

@@ -102,6 +102,10 @@ public class UserService {
         return userRepository.findByUsername(username);
     }
 
+    public Optional<User> findByEmail(String email) {
+        return userRepository.findByEmail(email);
+    }
+
     public Optional<User> findById(Long id) {
         return userRepository.findById(id);
     }