feat: expand Calamares installer with DM chooser, explicit DE packages, and custom packages module

- Add packagechooser@dm instance for display manager selection (SDDM/LightDM/LXDM/LY)
- Expand desktop environment package lists (Xfce MATE LXQt i3) with explicit packages
- Change plasma -> plasma-meta and lsb-release -> antergos-lsb-release
- Add bootloader, displaymanager, grubcfg, postcfg, services-artix module configs
- Install antergos-release, antergos-wallpapers, antergos-grub-theme via basestrap
- Add custom packages/main.py with one-at-a-time install and --overwrite='*'
- Add --overwrite='*' to basestrap main.py for pacman -Sy operations

iso-profiles/antergos/live-overlay/etc/calamares/modules/bootloader.conf

@@ -0,0 +1,21 @@
+---
+efiBootLoader: "grub"
+
+kernel: "/vmlinuz-linux-x86_64"
+img: "/initramfs-linux-x86_64.img"
+fallback: "/initramfs-linux-x86_64-fallback.img"
+timeout: "10"
+
+grubInstall: "grub-install"
+grubMkconfig: "grub-mkconfig"
+grubCfg: "/boot/grub/grub.cfg"
+grubProbe: "grub-probe"
+efiBootMgr: "efibootmgr"
+
+installEFIFallback: true
+
+efiBootloaderId: "Antergos"
+
+# installHybridGRUB: false
+
+# efiBootLoaderVar: "packagechooser_bootloader"