Use Forgejo workflows and registry

.forgejo/workflows/publish.yml

@@ -0,0 +1,43 @@
+name: publish-image
+on:
+  push:
+    tags: ['v*']
+
+jobs:
+  docker:
+    runs-on: docker
+    container:
+      image: catthehacker/ubuntu:act-22.04
+      volumes:
+        - /certs/client:/certs/client
+    env:
+      DOCKER_HOST: tcp://docker:2376
+      DOCKER_TLS_VERIFY: "1"
+      DOCKER_CERT_PATH: /certs/client
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/login-action@v3
+        with:
+          registry: git.snakedesert.se
+          # Forgejo exposes github.* compatibility aliases; this matches the
+          # established Porchlight workflow and works with older runners.
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
+      - uses: docker/metadata-action@v5
+        id: meta
+        with:
+          images: git.snakedesert.se/${{ github.repository }}
+          tags: |
+            type=ref,event=tag
+            type=semver,pattern={{version}}
+            type=raw,value=latest
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          target: prod
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}