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_

Reproduce the report by starting copilot-cli with a moderate task that launches a background agent, then capture the rate-limit response and request ID. Compare the displayed guidance with Copilot usage/settings and the linked Terms of Service; done means the limit condition and an actionable recovery path are communicated clearly.

Written by the indexing model from the issue text.