Stage 4: Calamares installer and Btrfs snapshots (0.2.0)

- Package Calamares 3.4.3 (Qt6, widgets UI) with xbps-src.
- das-installer: Calamares setup for Void/runit with Das OS branding and
  slides. It copies the clean live image (live-base), builds locales and the
  host-only initramfs, rewrites kernels without sparse tails (GRUB 2.12 cannot
  read Btrfs holes at the end of a file), then removes itself.
- das-snapshots: flat Btrfs layout (@, @home, @snapshots, @var_log,
  @var_cache_xbps), snapper with hourly snapshots via cronie, grub-btrfs menu,
  snapper-rollback, and a dracut module that boots read-only snapshots with
  a RAM overlay.
- das-settings 0.2.0: start LightDM with the system locale.
- Live image: GRUB, efibootmgr and the new packages; Das OS /etc/issue.
- Build: wipe stale destdirs before building packages.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/container/build-iso.sh

@@ -43,6 +43,9 @@ for pattern in 'echo void-live >' 'voidlinux'; do
   fi
 done
 sed -i -e 's/echo void-live >/echo dasos >/' -e 's/voidlinux/live/g' "$adduser"
+# mklive copies its /etc/issue (Void live logins) into the image, and the
+# installer copies the image to disk, so use a neutral Das OS one.
+cp /work/live/branding/issue /opt/void-mklive/data/issue
 
 rsvg-convert /work/live/branding/splash.svg --output "$work/splash.png"
 rm -f "$iso"