added start backend

src/main/java/com/krylov/refound/service/security/CustomUserDetailsService.java

@@ -0,0 +1,27 @@
+package com.krylov.refound.service;
+
+import com.krylov.refound.entity.User;
+import com.krylov.refound.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.core.userdetails.UserDetailsService;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class CustomUserDetailsService  implements UserDetailsService {
+  private final UserRepository repository;
+
+  @Override
+  public UserDetails loadUserByUsername(String email) {
+    User user = repository.findByEmail(email)
+        .orElseThrow(() -> new UsernameNotFoundException("User not found"));
+
+    return org.springframework.security.core.userdetails.User
+        .withUsername(user.getEmail())
+        .password(user.getPassword())
+        .authorities("USER")
+        .build();
+  }
+}