Execution timer for `shell` tool

### Describe the feature or problem you'd like to solve

Lack of information for how long a shell job has been running

### Proposed solution

The shell tool should give a timer of how many seconds that a command has been running for.

### Example prompts or workflows

Login to a system, check counts for X every 5s for 15s.

### Additional context

This is really useful in scenarios where you want to know how long has it been going for, so that means you know when its hits 15s the work is about to be over rather than a blind wait.

先找到 shell 工具的執行進入點，並追蹤執行命令時如何呈現給使用者。確認在命令執行期間可以在哪裡顯示經過時間，接著使用一個持續 15 秒、每 5 秒檢查一次計數的工作流程來驗證計時器。完成的標準是使用者可以看到 shell 工作已經執行了多少秒。

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