refactor(auth): make admin user initialization idempotent

- Check if admin user already exists before inserting
- Improve log messages with descriptive output
- Move @Transactional annotation to run method
- Fix minor formatting inconsistency

src/main/kotlin/com/msksbr/bookmgr/runner/InitUserRunner.kt

@@ -16,60 +16,57 @@ class InitUserRunner(
     val userMapper: UserMapper,
 ) : ApplicationRunner {
     private val logger = LoggerFactory.getLogger(InitUserRunner::class.java)
+
     // 添加注解，失败时可回滚
     @Transactional
     override fun run(args: ApplicationArguments) {
-        logger.info("Init user")
-        insertUser()
-        logger.info("Init user complete")
-    }
-
-    fun insertUser() {
-        // 创建admin账户
-        logger.info("create admin user")
-        val admin = User(
-            null,
-            "admin",
-            // 1. 使用 Argon2 对密码进行哈希处理（自动包含随机 salt）
-            // 2. encode() 来自 Java 接口，Kotlin 会将返回值视为平台类型，因此这里断言非空
-            passwordEncoder.encode("admin")!!,
-            "admin"
-        )
-        logger.info("insert common user")
-        // 创建普通账户
-        val user = User(
-            null,
-            "user",
-            passwordEncoder.encode("user")!!,
-            "user"
-        )
-        // 插入到数据库
-        // 先查询数据库中是否有admin账户
-        logger.info("select admin user from database")
+        logger.info("Starting default user initialization")
+        logger.debug("Querying for admin user")
         val existsAdmin = userMapper.selectOne(
             QueryWrapper<User>()
-                .eq("username", admin.username)
+                .eq("username", "admin")
         )
-        // 没有则插入
         if (existsAdmin == null) {
-            logger.info("admin user not found")
-            logger.info("insert admin user to database")
-            userMapper.insert(admin)
+            logger.info("Admin user not found, creating...")
+            insertAdminUser()
         } else {
-            logger.info("found exists admin user")
+            logger.debug("Admin user already exists, skipping")
         }
-
-        logger.info("select common user from database")
+        logger.debug("Querying for common user")
         val existsUser = userMapper.selectOne(
             QueryWrapper<User>()
-                .eq("username", user.username)
+                .eq("username", "user01")
         )
         if (existsUser == null) {
-            logger.info("common user not found")
-            logger.info("insert common user to database")
-            userMapper.insert(user)
+            logger.info("Common user not found, creating...")
+            insertCommonUser()
         } else {
-            logger.info("found exists common user")
-        }
+            logger.debug("Common user already exists, skipping")
+        }
+        logger.info("Default user initialization completed")
+    }
+
+    fun insertAdminUser() {
+        val user = User(
+            id = null,
+            username = "admin",
+            password = passwordEncoder.encode("admin")!!,
+            role = "admin"
+        )
+        logger.debug("Creating admin user: username={}, role={}", user.username, user.role)
+        userMapper.insert(user)
+        logger.info("Admin user created successfully")
+    }
+
+    fun insertCommonUser() {
+        val user = User(
+            id = null,
+            username = "user01",
+            password = passwordEncoder.encode("user01")!!,
+            role = "user"
+        )
+        logger.debug("Creating common user: username={}, role={}", user.username, user.role)
+        userMapper.insert(user)
+        logger.info("Common user created successfully")
     }
 }