ci: mirror Docker images to daddelolymp registry

After building and pushing to adriahub, the CI pipeline now also
tags and pushes images to forgejo.daddelolymp.de as a backup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.forgejo/workflows/build-deploy.yml

@@ -6,6 +6,7 @@ on:
 
 env:
   REGISTRY: forgejo.adriahub.de
+  REGISTRY_MIRROR: forgejo.daddelolymp.de
   IMAGE: root/gaming-hub
 
 jobs:
@@ -58,7 +59,7 @@ jobs:
               ${{ env.REGISTRY }}/${{ env.IMAGE }}:latest
           fi
 
-      - name: Push to registry
+      - name: Push to registry (adriahub)
         run: |
           echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login ${{ env.REGISTRY }} -u root --password-stdin
           docker push ${{ env.REGISTRY }}/${{ env.IMAGE }}:${{ steps.vars.outputs.tag }}
@@ -66,6 +67,18 @@ jobs:
             docker push ${{ env.REGISTRY }}/${{ env.IMAGE }}:latest
           fi
 
+      - name: Mirror to registry (daddelolymp)
+        run: |
+          echo "${{ secrets.REGISTRY_DADDELOLYMP_PASSWORD }}" | docker login ${{ env.REGISTRY_MIRROR }} -u root --password-stdin
+          docker tag ${{ env.REGISTRY }}/${{ env.IMAGE }}:${{ steps.vars.outputs.tag }} \
+            ${{ env.REGISTRY_MIRROR }}/${{ env.IMAGE }}:${{ steps.vars.outputs.tag }}
+          docker push ${{ env.REGISTRY_MIRROR }}/${{ env.IMAGE }}:${{ steps.vars.outputs.tag }}
+          if [ "${GITHUB_REF_NAME}" = "main" ]; then
+            docker tag ${{ env.REGISTRY }}/${{ env.IMAGE }}:latest \
+              ${{ env.REGISTRY_MIRROR }}/${{ env.IMAGE }}:latest
+            docker push ${{ env.REGISTRY_MIRROR }}/${{ env.IMAGE }}:latest
+          fi
+
   deploy:
     runs-on: ubuntu-latest
     needs: build