Create a notification when model is stopping due to content filtering

Create a notification when model is stopping due to content filtering

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| Field | Value |
| --- | --- |
| App version | 1.0.23 |
| OS | Windows 10.0.26220 |
| Theme | Notionish |
| Path | /chat |
| Tenure | Week 9 |

Start from the /chat flow and trace where model stopping and content filtering are handled. Identify the existing notification or message presentation path, then define done as showing a clear notification when filtering stops the model; the issue names no files or tests, so confirm the expected wording and UI with a maintainer.

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