Add Docker support with Dockerfile and entrypoin

.forgejo/workflows/docker.yml

@@ -0,0 +1,32 @@
+name: Docker
+
+on:
+  release:
+    types:
+      - published
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set image tag
+        id: meta
+        run: echo "TAG=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+
+      - name: Login to Forgejo registry
+        uses: docker/login-action@v3
+        with:
+          registry: git.sinfonie.org
+          username: ${{ secrets.REGISTRY_USER }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
+      - name: Build image
+        run: |
+          docker build -t git.sinfonie.org/sinfonie/photo26:${{ steps.meta.outputs.TAG }} .
+
+      - name: Push image
+        run: |
+          docker push git.sinfonie.org/sinfonie/photo26:${{ steps.meta.outputs.TAG }}
+