ci: publish an Arch package to the Gitea registry on release

.gitea/workflows/arch-package.yml

@@ -0,0 +1,57 @@
+name: Arch package
+
+# Builds the qtpotato package from a release tag and publishes it to this Gitea's Arch
+# registry, so users can install it with pacman until it is on the AUR.
+on:
+  push:
+    tags: ['v*']
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: Release tag to package, e.g. v0.1.0
+        required: true
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  package:
+    # Arch Linux only ships x86_64 images, so pick an amd64 runner.
+    runs-on: amd64
+    container: archlinux:latest
+    env:
+      TAG: ${{ inputs.tag || github.ref_name }}
+    steps:
+      - name: Install dependencies
+        run: |
+          pacman -Syu --noconfirm --needed git nodejs base-devel cmake ninja extra-cmake-modules \
+              qt6-base qt6-declarative kirigami ki18n kcoreaddons kcrash kconfig \
+              mpvqt qcoro qtkeychain-qt6 ffmpeg hicolor-icon-theme
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ inputs.tag || github.ref }}
+      - name: Build
+        run: |
+          version="${TAG#v}"
+          dir=/tmp/pkg
+          mkdir -p "$dir"
+          git config --global --add safe.directory "$PWD"
+          git archive --format=tar --prefix="qtpotato-$version/" HEAD | gzip -n > "$dir/qtpotato-$version.tar.gz"
+          sum="$(sha256sum "$dir/qtpotato-$version.tar.gz" | cut -d' ' -f1)"
+          sed -e "s/^pkgver=.*/pkgver=$version/" -e "s/^pkgrel=.*/pkgrel=1/" \
+              -e 's/^source=.*/source=("$pkgname-$pkgver.tar.gz")/' \
+              -e "s/^sha256sums=.*/sha256sums=('$sum')/" \
+              packaging/aur/qtpotato/PKGBUILD > "$dir/PKGBUILD"
+          # makepkg refuses to run as root.
+          useradd -m builder
+          chown -R builder "$dir"
+          su builder -c "cd $dir && makepkg --noconfirm"
+      - name: Publish
+        env:
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          for f in /tmp/pkg/qtpotato-[0-9]*.pkg.tar.zst; do
+              curl -fsS -X PUT -H "Authorization: token $TOKEN" --upload-file "$f" \
+                  "$GITHUB_SERVER_URL/api/packages/${GITHUB_REPOSITORY%%/*}/arch/qtpotato"
+          done

README.md

@@ -24,6 +24,42 @@ translate a whole subtitle track with any OpenAI-compatible API and show the res
   auto-hiding controls.
 - Follows your Plasma style, colours and icons.
 
+## Installing on Arch Linux
+
+### From the pacman repository
+
+Every release is built and published to this Gitea's package registry. Import the signing key
+once:
+
+```sh
+curl -O https://git.trivk.dev/api/packages/tri/arch/repository.key
+sudo pacman-key --add repository.key
+sudo pacman-key --lsign-key 9C48725295A5F54A6A491CF86B273DD49890E8A7
+```
+
+Then add the repository to `/etc/pacman.conf` and install:
+
+```ini
+[qtpotato]
+SigLevel = Required
+Server = https://git.trivk.dev/api/packages/tri/arch/$repo/$arch
+```
+
+```sh
+sudo pacman -Sy qtpotato
+```
+
+The package is built against Arch's current Qt and KDE Frameworks. If it breaks after a system
+update before a new release is out, build it from source as below.
+
+### From the PKGBUILD
+
+```sh
+git clone https://git.trivk.dev/tri/QtPotato.git
+cd QtPotato/packaging/aur/qtpotato   # or qtpotato-git for the latest main
+makepkg -si
+```
+
 ## Building
 
 ### Dependencies