fix: 修复所有 golangci-lint 错误

- goimports: 修复 3 个文件的导入顺序
- ineffassign: 移除无效的变量初始化
- staticcheck SA9003: 修复空分支问题

server/global/session/session.go

@@ -3,10 +3,11 @@ package session
 import (
 	"next-terminal/server/common/guacamole"
 	"next-terminal/server/common/term"
+	"next-terminal/server/dto"
+
 	"sync"
 
 	"github.com/gorilla/websocket"
-	"next-terminal/server/dto"
 )
 
 type Session struct {