Add setting to restrict actions to the current repo

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

If I ask copilot to pull the issues, or create a new issue, it is possible that it uses the wrong owner / repo and pull random issues or tries to create issues on non-existing repos.

Then after an error, it runs `git remote -v` or calls the tool `get_me` and re-does the action.

For now, it never happened that it created issues on other people repos, but it would like to exclude the possibility entirely.

### Proposed solution

Add a setting to restrict all actions to the current repo.
This would remove the "owner" and "repo" from all tool calls.

### Example prompts or workflows (for tools/toolsets only)

### Additional context

For example, the "add comment to issue" tool would become:

```
{
"body": "....",
"issue_number": 109
}
```

No files or tests are named in the issue. Start by tracing how the current repository is determined and how owner/repo are passed to each GitHub action, then identify the setting entry point and all affected tools. Done means the setting consistently restricts actions to the current repository and is covered by tests for representative issue operations.

索引モデルが issue の本文から書いたものです。