add forgejo actions workflow for container building

.forgejo/workflows/container.yml

@@ -0,0 +1,36 @@
+name: Build Container
+
+on:
+  push: {}
+
+permissions:
+  packages: write
+
+jobs:
+  build-container:
+    name: Build Container
+    runs-on: docker
+    container:
+      image: ghcr.io/osscontainertools/kaniko:alpine
+    steps:
+      - name: Install NodeJS for actions compatibility
+        run: apk add --no-cache nodejs
+      - name: Checkout source code
+        uses: actions/checkout@v6
+      - name: Login to container registry (prod only)
+        if: ${{ forgejo.ref_name == 'main' }}
+        run: /kaniko/executor login --username="forgejo-actions" --password="${{ forgejo.token }}"
+      - name: Build Container
+        env:
+          KANIKO_NO_PUSH: ${{ forgejo.ref_name != 'main' }}
+        run: /kaniko/executor
+          --dockerfile="${{forgejo.workspace }}/Containerfile"
+          --context="dir://${{ forgejo.workspace }}"
+          --destination=git.hamburg.ccc.de/ccchh/dooris:latest
+          --credential-helpers=env
+          --no-push-cache
+          --annotation=org.opencontainers.image.ref.name=dooris
+          --annotation=org.opencontainers.image.url=${{ forgejo.server_url }}/${{ forgejo.repository }}
+          --annotation=org.opencontainers.image.source=${{ forgejo.server_url }}/${{ forgejo.repository }}
+          --annotation=org.opencontainers.image.licenses=AGPL-3.0
+