Add system user and log attribution

backend/src/main/java/com/openisle/config/SystemUserInitializer.java

@@ -0,0 +1,34 @@
+package com.openisle.config;
+
+import com.openisle.model.Role;
+import com.openisle.model.User;
+import com.openisle.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.stereotype.Component;
+
+/**
+ * Ensure a dedicated "system" user exists for internal operations.
+ */
+@Component
+@RequiredArgsConstructor
+public class SystemUserInitializer implements CommandLineRunner {
+    private final UserRepository userRepository;
+    private final PasswordEncoder passwordEncoder;
+
+    @Override
+    public void run(String... args) {
+        userRepository.findByUsername("system").orElseGet(() -> {
+            User system = new User();
+            system.setUsername("system");
+            system.setEmail("system@openisle.local");
+            system.setPassword(passwordEncoder.encode("system"));
+            system.setRole(Role.ADMIN);
+            system.setVerified(true);
+            system.setApproved(true);
+            return userRepository.save(system);
+        });
+    }
+}
+