Add CI workflow to build and publish packages to Gitea Registry

Triggers on PKGBUILD changes (from pkgver-bot commits).
Builds the changed package with makepkg and uploads the
.pkg.tar.zst to the Gitea Arch Package Registry.

.gitea/workflows/build-and-publish.yaml

@@ -0,0 +1,68 @@
+# ABOUTME: Builds changed packages and publishes them to Gitea Package Registry.
+# ABOUTME: Triggered by pkgver-bot commits (from per-project CI workflows).
+
+name: Build and publish packages
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - '*/PKGBUILD'
+
+jobs:
+  detect-changes:
+    runs-on: moonarch
+    steps:
+      - name: Detect changed PKGBUILDs
+        run: |
+          git clone http://gitea:3000/nevaforget/moonarch-pkgbuilds.git repo
+          cd repo
+
+          CHANGED=$(git diff --name-only HEAD~1 HEAD | grep '/PKGBUILD$' | sed 's|/PKGBUILD||' || true)
+
+          if [ -z "$CHANGED" ]; then
+            echo "No PKGBUILD changes detected"
+            exit 0
+          fi
+
+          echo "Changed packages: $CHANGED"
+
+          for pkg in $CHANGED; do
+            echo "==> Building $pkg"
+            cd "$pkg"
+
+            # Build package (skip dep checks — deps are already installed or in optdepends)
+            makepkg -sfd --noconfirm
+
+            # Find the built package file
+            PKG_FILE=$(ls -t *.pkg.tar.zst 2>/dev/null | head -1)
+            if [ -z "$PKG_FILE" ]; then
+              echo "ERROR: No package file found for $pkg"
+              cd ..
+              continue
+            fi
+
+            # Extract version for delete endpoint
+            PKG_NAME=$(grep '^pkgname=' PKGBUILD | cut -d= -f2)
+            PKG_VER=$(grep '^pkgver=' PKGBUILD | cut -d= -f2)
+            PKG_REL=$(grep '^pkgrel=' PKGBUILD | cut -d= -f2)
+            PKG_ARCH=$(grep '^arch=' PKGBUILD | sed "s/.*('\(.*\)').*/\1/")
+            FULL_VER="${PKG_VER}-${PKG_REL}"
+
+            echo "==> Uploading $PKG_FILE ($PKG_NAME $FULL_VER $PKG_ARCH)"
+
+            # Delete old version if it exists (ignore 404)
+            curl -s -X DELETE \
+              -H "Authorization: token ${{ secrets.PKG_REGISTRY_TOKEN }}" \
+              "https://gitea.moonarch.de/api/packages/nevaforget/arch/moonarch/${PKG_NAME}/${FULL_VER}/${PKG_ARCH}" || true
+
+            # Upload new version
+            curl -s \
+              -H "Authorization: token ${{ secrets.PKG_REGISTRY_TOKEN }}" \
+              --upload-file "$PKG_FILE" \
+              "https://gitea.moonarch.de/api/packages/nevaforget/arch/moonarch"
+
+            echo "==> Published $PKG_NAME $FULL_VER"
+            cd ..
+          done