feat: add Arch Linux package and CI workflow

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/arch-publish.yml

@@ -0,0 +1,52 @@
+name: Build and Publish Arch Package
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  build-arch:
+    runs-on:
+      - ubuntu-24.04
+    container:
+      image: archlinux:latest
+    steps:
+      - name: Install build dependencies
+        run: pacman -Syu --noconfirm git nodejs go base-devel curl
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Create build user
+        run: |
+          useradd -m build
+          echo "build ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
+          chown -R build:build .
+
+      - name: Configure git safe directory
+        run: git config --global --add safe.directory "$PWD"
+
+      - name: Prepare source
+        run: |
+          pkgver=$(echo "${{ github.ref_name }}" | sed 's/^v//')
+          pkgname="axolotl"
+
+          sed -i "s/pkgver=.*/pkgver=$pkgver/" packaging/arch/PKGBUILD
+
+          git archive --format=tar.gz --prefix="$pkgname-$pkgver/" -o "packaging/arch/$pkgname-$pkgver.tar.gz" HEAD
+
+          sha=$(sha512sum "packaging/arch/$pkgname-$pkgver.tar.gz" | awk '{print $1}')
+          sed -i "s|source=.*|source=(\"$pkgname-$pkgver.tar.gz\")|" packaging/arch/PKGBUILD
+          sed -i "s|sha512sums=.*|sha512sums=('$sha')|" packaging/arch/PKGBUILD
+          chown -R build:build .
+
+      - name: Build package
+        run: su build -c "cd $PWD/packaging/arch && makepkg -s --noconfirm"
+
+      - name: Publish to Gitea Registry
+        run: |
+          pkg_file=$(find $PWD/packaging/arch -name "*.pkg.tar.zst" -type f | head -1)
+          curl --fail-with-body \
+            --user "${{ github.repository_owner }}:${{ secrets.ACCESS_TOKEN }}" \
+            --upload-file "$pkg_file" \
+            "${{ github.server_url }}/api/packages/${{ github.repository_owner }}/arch/push"