Add in-house Calamares package (AUR-only upstream)

Calamares isn't in Arch's official repos, so BOS vendors the PKGBUILD and
publishes a built package to the [breadway] repo. All its deps are official
(kpmcore, qt6-*, yaml-cpp). Also drop the nonexistent calamares-qt6 from the
package list (calamares 3.4.x is already Qt6).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.forgejo/workflows/calamares.yml

@@ -0,0 +1,35 @@
+name: Build and publish calamares
+
+# Calamares is AUR-only (not in Arch's official repos), so BOS maintains an
+# in-house PKGBUILD and publishes the built package to the [breadway] repo.
+on:
+  push:
+    paths:
+      - 'packaging/calamares/**'
+  workflow_dispatch:
+
+jobs:
+  calamares:
+    runs-on: [self-hosted, hestia]
+    container:
+      image: archlinux:latest
+    steps:
+      - name: Build and publish
+        env:
+          PUBLISH_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
+        run: |
+          set -euo pipefail
+          pacman -Syu --noconfirm base-devel git cmake ninja \
+            extra-cmake-modules qt6-tools qt6-translations libglvnd \
+            kcoreaddons kpmcore libpwquality qt6-declarative qt6-svg yaml-cpp
+          useradd -m builder
+          git config --global --add safe.directory '*'
+          git clone --depth 1 "https://git.breadway.dev/${GITHUB_REPOSITORY}.git" /home/builder/src
+          chown -R builder:builder /home/builder/src
+          su builder -c "cd /home/builder/src/packaging/calamares && makepkg -f --noconfirm --nocheck"
+          PKG=$(find /home/builder/src/packaging/calamares -name '*.pkg.tar.zst' | head -1)
+          curl -fsS -X PUT \
+            -H "Authorization: token ${PUBLISH_TOKEN}" \
+            -H "Content-Type: application/octet-stream" \
+            --data-binary "@${PKG}" \
+            "https://git.breadway.dev/api/packages/Breadway/arch/os"