新增：Markdown编辑器/数据库优化/安全修复

- Markdown 编辑器：实时预览、PDF 导出、独立查看器
- 数据库优化：动态连接池、查询缓存、Redis Pipeline
- 窗口置顶功能
- 文件系统增强：右键菜单、编辑器集成、收藏夹重构
- 安全修复：XSS 防护、路径穿越、HTML 注入
- 代码质量：正则预编译、缓存锁优化、死代码清理

internal/service/connection_service.go

@@ -1,12 +1,16 @@
 package service
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"u-desk/internal/crypto"
 	"u-desk/internal/dbclient"
 	"u-desk/internal/storage/models"
 	"u-desk/internal/storage/repository"
+
+	"gorm.io/gorm"
 )
 
 // ConnectionService 连接管理服务
@@ -90,8 +94,20 @@ func (s *ConnectionService) GetConnection(id uint) (*models.DbConnection, error)
 	return s.repo.FindByID(id)
 }
 
-// DeleteConnection 删除连接配置
+// DeleteConnection 删除连接配置（含关联数据和连接池清理）
 func (s *ConnectionService) DeleteConnection(id uint) error {
+	conn, err := s.repo.FindByID(id)
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil // 连接不存在视为成功
+		}
+		return fmt.Errorf("获取连接配置失败: %v", err)
+	}
+
+	// 关闭连接池中的连接
+	dbclient.GetPool().CloseConnection(id, conn.Type)
+
+	// 删除连接记录
 	return s.repo.Delete(id)
 }
 
@@ -185,3 +201,68 @@ func (s *ConnectionService) TestConnectionWithParams(connType, host string, port
 		return fmt.Errorf("不支持的数据库类型: %s", connType)
 	}
 }
+
+// LoadAllDatabases 加载全部数据库列表
+func (s *ConnectionService) LoadAllDatabases(dbType, host string, port int, username, password, database, options string, existingId uint) ([]string, error) {
+	// 如果是编辑模式且密码为空，尝试获取已保存的密码
+	actualPassword := password
+	if existingId > 0 && password == "" {
+		conn, err := s.repo.FindByID(existingId)
+		if err != nil {
+			return nil, fmt.Errorf("获取原连接配置失败: %v", err)
+		}
+		actualPassword, err = crypto.DecryptPassword(conn.Password)
+		if err != nil {
+			return nil, fmt.Errorf("密码解密失败: %v", err)
+		}
+	}
+
+	// 解析 MongoDB 选项
+	authSource := ""
+	authMechanism := ""
+	if options != "" {
+		var opts map[string]interface{}
+		if err := json.Unmarshal([]byte(options), &opts); err == nil {
+			authSource, _ = opts["authSource"].(string)
+			authMechanism, _ = opts["authMechanism"].(string)
+		}
+	}
+
+	switch dbType {
+	case "mysql":
+		return loadDatabasesForMySQL(host, port, username, actualPassword, database)
+	case "mongo":
+		return loadDatabasesForMongo(host, port, username, actualPassword, database, authSource, authMechanism)
+	case "redis":
+		return []string{}, nil
+	default:
+		return nil, fmt.Errorf("不支持的数据库类型: %s", dbType)
+	}
+}
+
+func loadDatabasesForMySQL(host string, port int, username, password, defaultDatabase string) ([]string, error) {
+	config := &dbclient.MySQLConfig{
+		Host: host, Port: port, Username: username,
+		Password: password, Database: defaultDatabase,
+	}
+	client, err := dbclient.NewMySQLClient(config)
+	if err != nil {
+		return nil, err
+	}
+	defer client.Close()
+	return client.ListDatabases(context.Background())
+}
+
+func loadDatabasesForMongo(host string, port int, username, password, defaultDatabase, authSource, authMechanism string) ([]string, error) {
+	config := &dbclient.MongoConfig{
+		Host: host, Port: port, Username: username,
+		Password: password, Database: defaultDatabase,
+		AuthSource: authSource, AuthMechanism: authMechanism,
+	}
+	client, err := dbclient.NewMongoClient(config)
+	if err != nil {
+		return nil, err
+	}
+	defer client.Close()
+	return client.ListDatabases(context.Background())
+}