ci: build frontend docker image in CI so compose can use it

Author: sjhallo07

.github/workflows/ci-integration.yml

@@ -24,6 +24,10 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
 
+      - name: Build frontend Docker image
+        run: |
+          docker buildx build --load -f server/frontend/Dockerfile -t xrwvm-frontend:ci server/frontend
+
       - name: Ensure docker-compose is available
         run: |
           docker version