fix: switch CI to Artix container, drop custom calamares build

- Change CI container from archlinux:latest to artixlinux/artixlinux:base-openrc
  so calamares and yad are available from Artix world repo directly
- Remove calamares from packages.yaml — no need to build it, Artix provides it
- Revert calamares PKGBUILD: put services-openrc back in skip list (unused)
- Packages now built by CI: wallpapers, yay, downgrade, keyring, mirrorlist,
  desktop-settings, branding, memes, welcome, hal, grub-theme, live

packages/calamares/PKGBUILD

@@ -41,6 +41,7 @@ build() {
     initramfscfg
     interactiveterminal
     packagechooser
+    services-openrc
   )
 
   local _pkgsrc_dir="$srcdir/$_pkgname-$pkgver"