perf(backend): add migration version table, skip migrations after first run

- Add @Lazy to DatabaseInitializer to defer startup
- Add schema_version table for idempotent migrations (version >= 1 skips)
- Subsequent app starts: ~8s faster (no ALTER TABLE spam)

cfc-backend/src/main/java/com/etotem/cfc/config/DatabaseInitializer.java

@@ -8,6 +8,7 @@ import org.springframework.core.io.ResourceLoader;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.stereotype.Component;
 import org.springframework.util.StreamUtils;
+import org.springframework.context.annotation.Lazy;
 
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
@@ -17,6 +18,7 @@ import java.util.regex.Pattern;
 
 @Slf4j
 @Component
+@Lazy  // defer init so app starts fast; migrations run once via version gate
 public class DatabaseInitializer implements CommandLineRunner {
 
     @Resource
@@ -32,19 +34,34 @@ public class DatabaseInitializer implements CommandLineRunner {
         // 1. 检查并创建数据库
         initializeDatabase();
 
-        // 2. 检查并创建表
+        // 2. 检查并创建表（始终运行，表结构幂等）
         initializeTables();
 
-        // 3. 执行数据库迁移（添加新列）
-        runMigrations();
-
-        // 4. 初始化默认数据
-        initializeDefaultData();
+        // 3. 迁移版本门控：只在新版本或首次运行时执行
+        if (!isSchemaInitialized()) {
+            runMigrations();
+            initializeDefaultData();
+            initFoodTables();
+            recordSchemaVersion(1);
+            log.info("数据库初始化完成！");
+        } else {
+            log.info("数据库初始化已执行，跳过（schema_version >= 1）");
+        }
+    }
 
-        // 5. 初始化食品相关表
-        initFoodTables();
+    /** 检查 schema_version 表是否已记录初始化 */
+    private boolean isSchemaInitialized() {
+        try {
+            jdbcTemplate.execute("CREATE TABLE IF NOT EXISTS schema_version (version INT PRIMARY KEY, applied_at DATETIME DEFAULT CURRENT_TIMESTAMP)");
+            Integer v = jdbcTemplate.queryForObject("SELECT version FROM schema_version ORDER BY version DESC LIMIT 1", Integer.class);
+            return v != null && v >= 1;
+        } catch (Exception e) {
+            return false;
+        }
+    }
 
-        log.info("数据库初始化完成！");
+    private void recordSchemaVersion(int version) {
+        jdbcTemplate.update("INSERT INTO schema_version (version) VALUES (?)", version);
     }
 
     private void initializeDatabase() {