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>

srcpkgs/das-installer/files/calamares/settings.conf

@@ -0,0 +1,54 @@
+# Calamares settings for Das OS (Void Linux, runit).
+---
+modules-search: [ local ]
+
+instances:
+- id: source
+  module: shellprocess
+  config: shellprocess-source.conf
+- id: postinstall
+  module: shellprocess
+  config: shellprocess-postinstall.conf
+- id: snapshot
+  module: shellprocess
+  config: shellprocess-snapshot.conf
+
+sequence:
+- show:
+  - welcome
+  - locale
+  - keyboard
+  - partition
+  - users
+  - summary
+- exec:
+  - partition
+  - mount
+  - shellprocess@source
+  - unpackfs
+  - machineid
+  - locale
+  - keyboard
+  - localecfg
+  - fstab
+  - users
+  - displaymanager
+  - networkcfg
+  - hwclock
+  - grubcfg
+  - shellprocess@postinstall
+  - packages
+  - bootloader
+  - shellprocess@snapshot
+  - umount
+- show:
+  - finished
+
+branding: dasos
+prompt-install: true
+dont-chroot: false
+oem-setup: false
+disable-cancel: false
+disable-cancel-during-exec: false
+hide-back-and-next-during-exec: true
+quit-at-end: false