docs: overhaul to match current repo reality (DE/DM selectors, SDDM pixie theme, overlays, offline installer, CI)

- index/installer/launcher: release facts, SDDM theme (pixie on master), init/DE selectors, NoExtract for Install Artix entry
- packages: branding pkg ships offline+online settings (no packagechooser.conf fallback), drop antergos-sddm-theme, correct repo index names
- overlays/overlay-root/overlay-live: root-overlay is live-session only, real file trees, symlinked settings.conf, commit reference
- desktop-environments/wallpapers: remove No Desktop option, video wallpaper via layan-theme + Smart Video Wallpaper Reborn
- ci/development/building: three workflows incl. ai-moderator, IA upload disabled (if:false)
- byode: new page documenting the SteamOS-inspired offline installer
- AGENTS.md/openrc: OpenRC was an installer-only dinit conflict; manual rc-update add works

docs/desktop-environments.md

@@ -80,13 +80,10 @@ Available desktops in online mode, sourced from Artix repos.
 | **Repo** | galaxy |
 | **Group** | `cosmic` |
 | **Session** | `cosmic.desktop` |
-| **Notes** | Rust-based, Wayland-native. Uses greetd + cosmic-greeter (not SDDM). Alpha quality, not for production. |
-
-## No Desktop
-
-Installs the base system only (TTY/login). Useful for servers or custom setups.
+| **Notes** | Rust-based, Wayland-native. Uses greetd + cosmic-greeter (not SDDM). Alpha quality, not for production. Select `greetd` in the display-manager chooser — `cosmic-greeter` requires the `greetd` daemon. |
 
 ## Not available
 
 - **Budgie** — not in any Artix repo (system, world, galaxy, lib32). Slideshow entries removed.
 - **GNOME** — dropped non-systemd support upstream. Not available.
+- **No Desktop** — a "no desktop / base only" option does not exist in the installer. Pick a DE from the list above.