Inaccessible `copilotd` release link in WSL Hosts setup

The WSL Hosts setup screen instructs users to download `copilotd` from: https://github.com/github/copilot-host/releases but that URL returns a 404.

### Steps to reproduce

1. Open GitHub Copilot App on Windows.
2. Go to the WSL Hosts setup/registration screen.
3. Click the `copilotd releases` link shown in the instructions.
4. Observe that the GitHub releases page returns 404.

### Actual behavior

The provided link is inaccessible:

https://github.com/github/copilot-host/releases

This blocks WSL host setup because the UI says `copilotd` must be installed inside the distro and available on PATH.

### Expected behavior

The app should link to a publicly accessible download page for the required `copilotd` binary, or provide another supported installation path.

### Additional context

The screen says:

> `copilotd` must be installed inside the distro and available on your login-shell PATH. Download a matching build from the `copilotd releases` page (this app is pinned to `copilotd v0.5.4`)...

Example command shown:

```bash
chmod +x ~/.local/bin/copilotd

Commencez par l’écran de configuration/enregistrement de WSL Hosts et suivez le lien `copilotd releases` affiché ainsi que les instructions d’installation. Vérifiez l’URL actuelle et l’exigence `copilotd v0.5.4` ; le travail est terminé lorsque l’écran pointe vers un téléchargement accessible au public ou un chemin d’installation pris en charge et que le lien ne renvoie plus 404.

Rédigé par le modèle d'indexation à partir du texte de l'issue.