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/overlays.md

@@ -0,0 +1,28 @@
+---
+title: Overlays
+layout: default
+nav_order: 10
+has_children: true
+---
+
+# Overlays
+
+Two directories under `iso-profiles/antergos/` control what goes into the ISO.
+
+```
+iso-profiles/antergos/
+├── profile.yaml
+├── root-overlay/     # → rootfs (squashfs)
+└── live-overlay/     # → live environment (initramfs)
+```
+
+## How overlays work
+
+- `root-overlay/` files are merged into the root squashfs — they become part of the installed system
+- `live-overlay/` files are copied into the live environment only — they're not present after installation
+- Overlays are **self-contained** (no symlinks to external directories) so the repo builds standalone
+- Live-overlay files are **copied** via `cp -LR` in `make_livefs()`, not overlay-mounted. Deleting a file from live-overlay exposes the package version underneath
+
+> **Disclaimer:** No symlinks were harmed in the making of this ISO. Well, maybe a few. We killed some.
+
+> Also: this ISO is 100% systemd-free. Not even a trace. We checked. Twice.