[Requests and ideas] Support standard Window menu actions in macOS Sequoia

## Summary

On macOS Sequoia, the GitHub Copilot desktop app does not expose the standard macOS Window menu actions that are available in most native desktop applications.

## Expected behavior

The **Window** menu should include standard macOS window management options such as:

* Move & Resize
* Full Screen Tile
* Fill
* Center
* Other Sequoia window management actions provided by the OS

For example, VS Code and many other desktop applications expose these options automatically through the Window menu.

## Actual behavior

In the GitHub Copilot desktop app, the Window menu only contains:

* Minimize
* Zoom
* Bring All to Front
* Move to Monitor

The newer macOS Sequoia window management actions are not available.

## Screenshots

* Screenshot 1: VS Code Window menu showing Move & Resize, Full Screen Tile, Fill, Center, etc.
* Screenshot 2: GitHub Copilot Window menu showing only Minimize, Zoom, Bring All to Front, and Move to Monitor.

## Why this matters

These menu items provide quick access to native macOS window management features and improve consistency with other desktop apps. Users expect standard Sequoia window controls to be available through the Window menu.

The issue names no files or tests. Start by locating the app's macOS Window menu setup and compare its current actions with the standard Sequoia options listed in the report. Done means the Window menu exposes Move & Resize, Full Screen Tile, Fill, Center, and other applicable native Sequoia window actions.

索引モデルが issue の本文から書いたものです。