Spamming server errors during subagent execution

### Describe the bug

There are a lot of transient server errors, especially during subagent tasks. Every time I run anything using fleet or anything that requires a subagent task, I'll get 10-15 or more copies of "Response was interrupted due to a server error. Retrying...".

Nothing seems to be affected, and the /tasks read-only view does not show any issues.

### Affected version

GitHub Copilot CLI 1.0.74-0

### Steps to reproduce the behavior

_No response_

### Expected behavior

It would be nice if the messages could be collapsed into one, for example, that updates a disruption count in place, or even just a little "Unstable connection, 5 retries" at the bottom somewhere.

### Additional context

_No response_

首先在 GitHub Copilot CLI 1.0.74-0 上复现一个 fleet 或 subagent 任务，并结合只读的 /tasks 视图观察重试消息。跟踪重复的 "Response was interrupted due to a server error. Retrying..." 消息在哪里发出；当临时重试通过一条折叠后的消息或中断计数来表示，且不改变任务行为时，即完成。

由索引模型根据 Issue 内容生成。