[Bug] Switching accounts does not refresh session history

When using multiple accounts, switching from one account to another does not refresh the session/chat history. After changing accounts, the application continues to display conversations from the previously selected account instead of loading the sessions associated with the newly selected account.

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| Field | Value |
| --- | --- |
| App version | 1.0.6 |
| OS | Windows 10.0.26200 |
| Theme | Notionish |
| Path | / |
| Tenure | Day 2 (Week 1) |

首先，使用两个账户在根路径下的桌面应用中复现该问题：切换账户，并观察显示的会话历史是否发生变化。跟踪账户切换和会话历史加载的入口点，然后验证仅显示属于新选定账户的对话。

由索引模型根据 Issue 内容生成。