Strange rate limit message

### Describe the bug

Today I started copilot-cli and gave it a quite moderate task.

It starts an background agent and about half a minute later failed with:

> Sorry, you've hit a rate limit that restricts the number of Copilot model requests you can make within a specific time period. Please try again in 2 hours. Please review our Terms of Service (https://docs.github.com/site-policy/github-terms/github-terms-of-service).
> (Request ID: AF08:1CC094:79C2BF:8F5AB7:69C609B2)

Apart from I find the error questionable (it unlikely has done many requests) I think copilot should get some means of reading the limits and take care it does not hit the error (e.g. it can gracefully stop working, throttling, ...) to give a better feedback to the user.

The link itself is rather useless on its own, as it has no indication about copilot limits at all, looking at the copilot settings and the usage shows nothing that explains the error or giving an indication what can be done from a users point of view to avoid the problem. All things are well withing the monthly limit.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

透過使用一個會啟動背景代理程式的中等任務啟動 copilot-cli 來重現該報告，然後擷取 rate-limit response 和 request ID。將顯示的指引與 Copilot 使用情況/設定以及連結的 Terms of Service 進行比較；當限制條件和可操作的復原路徑得到清楚傳達時，即表示完成。

由索引模型根據 Issue 內容生成。