ci(forgejo): configure act-runner container image and registry host

.forgejo/workflows/build-push.yml

@@ -12,17 +12,26 @@ on:
 jobs:
   build-and-push:
     runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
 
+      - name: Extract Registry Host
+        id: reg
+        run: |
+          # Strip protocol scheme (http:// or https://) for Docker registry reference
+          SERVER_HOST=$(echo "${{ gitea.server_url }}" | sed -e 's|^https\?://||')
+          echo "host=${SERVER_HOST}" >> "$GITHUB_OUTPUT"
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
       - name: Log in to Forgejo Container Registry
         uses: docker/login-action@v3
         with:
-          registry: ${{ gitea.server_url }}
+          registry: ${{ steps.reg.outputs.host }}
           username: ${{ gitea.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
@@ -30,7 +39,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ${{ gitea.server_url }}/${{ gitea.repository }}
+          images: ${{ steps.reg.outputs.host }}/${{ gitea.repository }}
           tags: |
             type=raw,value=latest,enable=${{ gitea.ref == 'refs/heads/main' || gitea.ref == 'refs/heads/master' }}
             type=ref,event=branch
@@ -51,6 +60,8 @@ jobs:
     needs: build-and-push
     if: (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master') || startsWith(github.ref, 'refs/tags/v')
     runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4