ci: remove auto-sync to deleted training Space

ci: also sync training_space/ to HF training Space on push

ci: bump actions/checkout to v5 and setup-python to v6 for Node 24

ci: install runtime deps alongside dev deps so sklearn is available in tests

ci: add GitHub Actions workflow to auto-sync to HF Space

ADA/mobile UI, pytest pythonpath, train_transformer PyArrow fix, enriched Explain Mode