Add an official gh.io shortlink for uninstall.sh

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

There is now an uninstall.sh script for curl/wget installs, but there is no matching official shortlink like gh.io/copilot-install. This makes uninstall instructions less consistent and harder to document as a stable one-line command.

### Proposed solution

Please create and maintain an official redirect such as https://gh.io/copilot-uninstall that points to the repository's uninstall.sh script. This would make the install and uninstall flows symmetrical and easier to document.

### Example prompts or workflows

- Install with curl -fsSL https://gh.io/copilot-install | bash
- Uninstall later with curl -fsSL https://gh.io/copilot-uninstall | bash
- Use matching shortlinks in README, support replies, and release notes

### Additional context

Adding uninstall.sh to the repository creates a raw GitHub URL, but it does not automatically create a gh.io shortlink. That redirect appears to require separate configuration outside the repository.