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/service/job_exec_shell.go

@@ -194,7 +194,7 @@ func (r ShellJob) executeShellByLocal() {
 	}
 
 	now := time.Now()
-	var msg = ""
+	var msg string
 	log.Debug("run local command", log.String("cmd", metadataShell.Shell))
 	output, outerr, err := utils.Exec(metadataShell.Shell)
 	if err != nil {