feat: domain registry is the landing page — muse / Version Anything hero (#31)

- Hero redesigned: large mono "muse" wordmark (gradient blue→purple), "Version Anything" as the subtitle in light uppercase tracking, removing the previous eyebrow + gradient h1 pattern - render_domain_registry.py now writes both domain_registry.html AND index.html (identical) so the registry IS the landing page at / - Page title simplified to "Muse — Version Anything" - Remove tools/render_index.py (superseded — no longer a separate page) - pages.yml: drop the render_index.py step (one fewer build step)

Co-authored-by: Gabriel Cardona <gabriel@tellurstori.com>