Notifications on the github app of remote sessions

### Describe the feature or problem you'd like to solve

If the agent is blocked on permission or user input, we should get notifications from github mobile app so that we can quickly unblock the agent

### Proposed solution

_No response_

### Example prompts or workflows

_No response_

### Additional context

_No response_

The issue does not name a file, test, or entry point. Start by mapping how Copilot CLI remote sessions represent permission or user-input blocks and how GitHub mobile notifications could surface them; done means a blocked agent reliably produces a useful notification that lets the user unblock it.

Written by the indexing model from the issue text.