Set up automated publishing to AUR

[Stephanvs]

Automate updates to Arch User Repository for hyprwt package.

Steps:

1. Create a new git repo on AUR (e.g., https://aur.archlinux.org/packages/hyprwt) if not exists.
2. In release.yml, add a job to:
   • Clone the AUR repo.
   • Update PKGBUILD with new pkgver, source URL, and sha256sum (compute from linux-x64.tar.gz).
   • Commit and push changes.
3. Use SSH key for auth (add to repo secrets).
4. Test by installing on Arch: yay -S hyprwt