feat: Agent CLI 与终端审计回放全面优化

- Agent CLI: 多轮对话、SSH 长连接、流式推理、Evolver 按用户隔离、历史侧栏
- 终端审计: 回放播放器、命令书签、筛选分页导出、命令输出统计、录制落盘修复
- 修复 session_commands 表迁移、Kill 竞态导致录制丢失、无录制会话回放提示
- 审计历史页只读（移除删除），移除回放弹框录制搜索

backend/pkg/remoteexec/executor.go

@@ -5,7 +5,6 @@ package remoteexec
 
 import (
 	"bytes"
-	"context"
 	"fmt"
 	"log"
 	"net"
@@ -70,10 +69,7 @@ type UploadResult struct {
 // 返回合并的 stdout+stderr 输出、退出码和错误。
 func Exec(cfg SSHConfig, command string, timeout time.Duration) (*ExecResult, error) {
 	start := time.Now()
-	result := &ExecResult{
-		Host: cfg.Host,
-		Port: cfg.Port,
-	}
+	result := &ExecResult{Host: cfg.Host, Port: cfg.Port}
 
 	client, err := connect(cfg)
 	if err != nil {
@@ -83,70 +79,7 @@ func Exec(cfg SSHConfig, command string, timeout time.Duration) (*ExecResult, er
 	}
 	defer client.Close()
 
-	// 创建 session
-	session, err := client.NewSession()
-	if err != nil {
-		result.Duration = time.Since(start).Milliseconds()
-		result.Error = fmt.Sprintf("创建SSH会话失败: %v", err)
-		return result, err
-	}
-	defer session.Close()
-
-	// 设置超时
-	ctx, cancel := context.WithTimeout(context.Background(), timeout)
-	defer cancel()
-
-	// 在 goroutine 中执行，支持超时
-	type execOut struct {
-		output []byte
-		err    error
-	}
-	ch := make(chan execOut, 1)
-
-	go func() {
-		var stdout, stderr bytes.Buffer
-		session.Stdout = &stdout
-		session.Stderr = &stderr
-		err := session.Run(command)
-
-		// 合并输出
-		output := stdout.Bytes()
-		if stderr.Len() > 0 {
-			if len(output) > 0 {
-				output = append(output, '\n')
-			}
-			output = append(output, stderr.Bytes()...)
-		}
-		ch <- execOut{output: output, err: err}
-	}()
-
-	select {
-	case <-ctx.Done():
-		result.Duration = time.Since(start).Milliseconds()
-		result.Error = fmt.Sprintf("执行超时（%v）", timeout)
-		result.ExitCode = -1
-		return result, fmt.Errorf("exec timeout after %v", timeout)
-	case out := <-ch:
-		result.Duration = time.Since(start).Milliseconds()
-		result.Output = string(out.output)
-
-		if out.err != nil {
-			if exitErr, ok := out.err.(*ssh.ExitError); ok {
-				result.ExitCode = exitErr.ExitStatus()
-				result.Success = false
-			} else {
-				result.ExitCode = -1
-				result.Error = out.err.Error()
-				result.Success = false
-				return result, out.err
-			}
-		} else {
-			result.ExitCode = 0
-			result.Success = true
-		}
-	}
-
-	return result, nil
+	return execWithClient(client, cfg, command, timeout)
 }
 
 // BatchExec 在多台远程主机上并发执行相同命令。