fix: rename tour_de_force.html → demo.html and update all references

- tools/tour_de_force.py: update docstring and output path - tools/render_domain_registry.py: update nav, hero CTA, and footer links - tools/README.md: update artifact table and open commands - docs/demo/tour-de-force-script.md: update file path in setup note - artifacts/tour_de_force.html: git mv'd to artifacts/demo.html