fix: packages.conf format, add init icons, instant wallpaper

- packages.conf: fix operations format (strings -> empty list)
- netinstall.yaml: remove empty Style group
- packagechooser.conf: add Breeze-style init system SVG icons
- wallpaper: pre-bake config in skel for instant wallpaper, remove wait loop
- AGENTS.md: add GPG signing instructions

iso-profiles/antergos/live-overlay/etc/calamares/modules/netinstall.yaml

@@ -59,11 +59,6 @@
     - artools-iso
     - artools-pkg
 
-- name: "Style"
-  description: "Antergos themes, icons, branding"
-  selected: false
-  packages: []
-
 - name: "Desktop"
   description: "DE"
   selected: true