Docker build cache disabled in CI

Routine Docker builds should reuse cache whenever possible. --no-cache and build action no-cache: true force every layer to rebuild, even when the Dockerfile and copied files are unchanged.

Use full no-cache rebuilds only for explicit refresh or debugging paths. For normal CI, prefer cache reuse, targeted cache busting, or --no-cache-filter for a specific stage.

- uses: docker/build-push-action@v6
  with:
    context: .