fix: 修复数据库持久化问题，添加dockerignore和启动日志

backend/internal/utils/database.go

@@ -41,8 +41,11 @@ func InitDB() {
 		})
 	default:
 		dbDir := filepath.Dir(cfg.FilePath)
-		if err := os.MkdirAll(dbDir, 0755); err != nil {
-			log.Fatalf("Failed to create database directory: %v", err)
+		if dbDir != "." && dbDir != "/" {
+			if err := os.MkdirAll(dbDir, 0755); err != nil {
+				log.Fatalf("Failed to create database directory %s: %v", dbDir, err)
+			}
+			log.Printf("Database directory ensured: %s", dbDir)
 		}
 		DB, err = gorm.Open(sqlite.Open(cfg.FilePath), &gorm.Config{
 			Logger: logger.Default.LogMode(logger.Info),
@@ -83,5 +86,7 @@ func AutoMigrate() {
 		log.Fatalf("Failed to migrate database: %v", err)
 	}
 
-	log.Println("Database migrated successfully")
+	var userCount int64
+	DB.Model(&models.User{}).Count(&userCount)
+	log.Printf("Database migrated successfully (users: %d)", userCount)
 }