- Replace docker buildx build in run-test.sh with docker/build-push-action
- Add GitHub Actions cache support (type=gha) to all test workflows
- Update run-test.sh to use pre-built images when available
- Maintain backward compatibility for local testing

This should significantly improve CI build times by leveraging
GitHub Actions cache instead of less efficient inline caching.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

- Remove cache options from driver-opts (not supported)
- Fix missing 'build' subcommand in test script
- Cache options are now properly passed to buildx build command

- Updated GitHub Actions workflow to use docker/setup-buildx-action@v3 with GitHub Actions cache
- Modified test/run-test.sh to use 'docker buildx' with cache-from and cache-to options
- All test jobs now share Docker layer cache, significantly reducing build times
- Uses cache-from=type=gha and cache-to=type=gha,mode=max for optimal caching

🤖 Generated with [Claude Code](https://claude.ai/code)

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

For now, srvrco is excluded.

The domain name will be <repo>-<os>-getssl.<duckdns.org|freedns.org>

Must be added to accounts on these services.

Note: To add the secrets to your repository on GitHub

Goto Actions -> Settings -> Secrets

New Repository Secret

Add DUCKDNS_TOKEN
Add DYNU_API_KEY

The test harness will suppress output unless an error occurs.

Upgrade testing was failing in forked repos CI because the
source repo was hard-coded.  Use the CI environment to use
the fork's repo.