Copilot app runs updater on every startup and then immediately offers another update

### Short summary

Almost every daily launch is blocked by the installer. After the update completes, the app frequently prompts for another update, causing repeated delays and disruption.

### Affected version or release

v1.0.26

### Installation context

Windows 11

### What happened?

When I open the GitHub Copilot app, the installer frequently starts before the app opens. After waiting for the update to install, the app launches and often immediately offers another update.

This may happen because updates are installed sequentially. For example, if version 1.0.1 is installed, version 1.0.2 is pending, and version 1.0.3 is already available, the app appears to install version 1.0.2 first and then offer version 1.0.3.

This behavior occurs almost every day and significantly delays access to the app.

### Steps to reproduce

1. Close the GitHub Copilot app and leave it closed until the next day.
2. Open the app.
3. Observe that the installer starts automatically before the app opens.

4. Wait for the installation to complete.
5. Allow the GitHub Copilot app to launch.
6. Observe that the app shortly afterward offers another update.

### Expected behavior

Updates should not block application startup. Preferably, Copilot should follow the Edge or VS Code update experience:

- Start the app immediately without launching the installer.
- Let the user confirm an update from within the app.
- If postponed, apply the update when the app shuts down.
- Check for the latest available version immediately before updating.
- Skip superseded intermediate versions. For example, an installation on version 1.0.1 should update directly to version 1.0.3 when version 1.0.2 is pending but version 3 is already available.

### Additional context

_No response_

The report identifies the Windows installer, application startup, and update-check flow but names no repository files or tests. Start by tracing how startup invokes the installer and how available versions are selected. Done means the app opens without a blocking update, checks the latest version before updating, and skips superseded versions without repeated prompts.

索引モデルが issue の本文から書いたものです。