Issue view can remain stale and overwrite newer issue content.

Sometimes the Issue view gets stuck on a stale view of the issue.
- The issue is changed on github.com but does not get updated in the github copilot app
- If I have a [ ] in the issue and I selected it in the GitHub copilot app it will override the description with the stale version.
- I can never get rid of the stale issue, no matter if I remove the session and restart it keeps showing the stale version.

Note:
Looks like Agents still pull the latest version for themselves when implementing the issue.

Seems like there are similarities to:
- #2421

---
| Field | Value |
| --- | --- |
| App version | 1.1.8 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 11 |

从 /chat issue 视图开始，将其显示的内容与 github.com 上当前的 issue 进行比较，并使用 #2421 作为相关上下文。复现报告中描述的过时视图和复选框选择操作序列。完成的标准是：视图会刷新为更新的 issue 内容，并且选择复选框不再用过时文本覆盖该内容，包括移除 session 并重启之后。

由索引模型根据 Issue 内容生成。