feat(website): promote the redesign to the home page

Move /redesign-sample to / and remove the previous marketing landing.

- Replaces the old BaseLayout/Nav/Hero-style home with the redesigned
  'Synaptic Cyan' page from PR #4
- Drops /redesign-sample — its content now lives at /
- Existing /install, /docs, /changelog, /community remain unchanged

Tracked in #3.

Author: IamCoder18