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/branding/dasos/slide-2.svg

@@ -0,0 +1,28 @@
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+  <defs>
+    <path id="petal" d="M0 0 L19.13 -46.19 L0 -92.39 L-19.13 -46.19 Z"/>
+    <path id="core" d="M0 -25.4 L8.61 -46.19 L0 -66.98 L-8.61 -46.19 Z"/>
+    <g id="pb"><use xlink:href="#petal" fill="#2f6fde"/><use xlink:href="#core" fill="#ffd23f"/></g>
+    <g id="py"><use xlink:href="#petal" fill="#f5c400"/><use xlink:href="#core" fill="#1f4fa8"/></g>
+    <g id="star">
+      <use xlink:href="#pb"/><use xlink:href="#py" transform="rotate(45)"/>
+      <use xlink:href="#pb" transform="rotate(90)"/><use xlink:href="#py" transform="rotate(135)"/>
+      <use xlink:href="#pb" transform="rotate(180)"/><use xlink:href="#py" transform="rotate(225)"/>
+      <use xlink:href="#pb" transform="rotate(270)"/><use xlink:href="#py" transform="rotate(315)"/>
+    </g>
+    <pattern id="stitch" patternUnits="userSpaceOnUse" width="28" height="20">
+      <path d="M14 0 L24 10 L14 20 L4 10 Z" fill="#2f6fde"/>
+      <path d="M14 6 L18 10 L14 14 L10 10 Z" fill="#f5c400"/>
+    </pattern>
+  </defs>
+  <rect width="800" height="440" fill="#f6f7fa"/>
+  <rect y="420" width="800" height="20" fill="url(#stitch)"/>
+  <use xlink:href="#star" transform="translate(150 210) scale(1.15)"/>
+  <g font-family="Inter, sans-serif" fill="#1f2430">
+    <text x="300" y="150" font-size="34" font-weight="600">Знімки системи</text>
+    <text x="300" y="205" font-size="19">Btrfs і snapper щогодини зберігають</text>
+    <text x="300" y="235" font-size="19">стан системи. Попередній знімок можна</text>
+    <text x="300" y="265" font-size="19">завантажити з меню GRUB і повернути</text>
+    <text x="300" y="295" font-size="19">командою sudo snapper-rollback.</text>
+  </g>
+</svg>