feat: add GitHub Pages docs site (Just the Docs), split packagechooser, disable IA upload

- docs/: new 13-page Jekyll site with Just the Docs theme
  - Home, Building, Installer, Packages, CI/CD, Development
  - Desktop Environments (with GNOME joke), Wallpapers, Launcher
  - Overlays, Root Overlay, Live Overlay
- .github/workflows/pages.yml: build & deploy docs from docs/ on
  push to master (only when docs/ changes)
- .github/workflows/build.yml: temporarily disable Internet Archive
  upload (if: false) until ISO is stable
- live-overlay/settings.conf: add instances section for init + desktop
  packagechooser instances
- live-overlay/modules/packagechooser_init.conf: init system selector
  (OpenRC, Runit, S6, Dinit) via netinstall-add method
- live-overlay/modules/packagechooser_desktop.conf: DE selector
  (Plasma, Xfce, Cinnamon, MATE, LXQt, i3, Sway, Hyprland + No Desktop)
  via legacy method
- README.md, AGENTS.md: fix sudo buildiso -> sudo ./buildiso, add note
  about system buildiso lacking --overwrite='*'
- .gitignore: add docs/_site/

docs/desktop-environments.md

@@ -0,0 +1,94 @@
+---
+title: Desktop Environments
+layout: default
+nav_order: 7
+---
+
+# Desktop Environments
+
+Available desktops in online mode, sourced from Artix repos.
+
+## Plasma (KDE)
+
+| | |
+|---|---|
+| **Repo** | world |
+| **Group** | `plasma` |
+| **Session** | `plasma.desktop` (Wayland) / `plasmax11.desktop` (X11) |
+| **Notes** | Default DE. Wayland is the default session. `plasma-wayland-session` is NOT a separate package on Artix — it's bundled in `plasma-workspace` |
+
+## Xfce
+
+| | |
+|---|---|
+| **Repo** | galaxy |
+| **Group** | `xfce4` |
+| **Session** | `xfce.desktop` |
+
+## Cinnamon
+
+| | |
+|---|---|
+| **Repo** | galaxy |
+| **Packages** | Individual (no meta-group) |
+| **Session** | `cinnamon.desktop` |
+
+## MATE
+
+| | |
+|---|---|
+| **Repo** | galaxy |
+| **Groups** | `mate` + `mate-extra` |
+| **Session** | `mate.desktop` |
+
+## LXQt
+
+| | |
+|---|---|
+| **Repo** | galaxy |
+| **Group** | `lxqt` |
+| **Session** | `lxqt.desktop` |
+
+## i3
+
+| | |
+|---|---|
+| **Repo** | world |
+| **Group** | `i3` |
+| **Session** | `i3.desktop` |
+
+## Sway
+
+| | |
+|---|---|
+| **Repo** | world |
+| **Packages** | `sway` + related |
+| **Session** | `sway.desktop` |
+
+## Hyprland
+
+| | |
+|---|---|
+| **Repo** | world |
+| **Packages** | `hyprland` |
+| **Session** | `hyprland.desktop` |
+
+## GNOME
+
+| | |
+|---|---|
+| **Repo** | imaginary |
+| **Group** | `gnome-systemd-hub` |
+| **Session** | `does-not-exist.desktop` |
+| **Status** | ❌ |
+
+> You really think you can get GNOME here? GNOME deleted all other init support. Take a walk.
+
+## Not available
+
+- **Budgie** — not in any Artix repo (system, world, galaxy, lib32). Slideshow entries removed.
+- **GNOME** — see above.
+
+## No Desktop
+
+Installs the base system only (TTY/login). Useful for servers or custom setups.