feature: 实现数据库实例管理

server/internal/db/infrastructure/persistence/persistence.go

@@ -3,11 +3,16 @@ package persistence
 import "mayfly-go/internal/db/domain/repository"
 
 var (
+	instanceRepo  repository.Instance  = newInstanceRepo()
 	dbRepo        repository.Db        = newDbRepo()
 	dbSqlRepo     repository.DbSql     = newDbSqlRepo()
 	dbSqlExecRepo repository.DbSqlExec = newDbSqlExecRepo()
 )
 
+func GetInstanceRepo() repository.Instance {
+	return instanceRepo
+}
+
 func GetDbRepo() repository.Db {
 	return dbRepo
 }