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/modules/users.conf

@@ -0,0 +1,53 @@
+---
+defaultGroups:
+    - name: users
+      must_exist: true
+      system: true
+    - name: wheel
+      must_exist: true
+      system: true
+    - audio
+    - video
+    - input
+    - storage
+    - network
+    - optical
+    - scanner
+    - lp
+    - kvm
+    - plugdev
+    - name: bluetooth
+      must_exist: false
+      system: true
+
+sudoersGroup: wheel
+sudoersConfigureWithGroup: true
+autologinGroup: autologin
+
+setRootPassword: true
+doReusePassword: true
+displayAutologin: true
+doAutologin: false
+
+passwordRequirements:
+    minLength: 4
+    maxLength: -1
+allowWeakPasswords: true
+allowWeakPasswordsDefault: true
+
+user:
+    shell: /bin/bash
+    forbidden_names: [ root, live ]
+    home_permissions: "o700"
+
+hostname:
+    location: EtcFile
+    writeHostsFile: true
+    template: "${login}-dasos"
+    forbidden_names: [ localhost ]
+
+presets:
+    fullName:
+        editable: true
+    loginName:
+        editable: true