#88 FTX-88: Restyle landing page with Rodmena brand theme

EARS SPEC:\n- LX-1: The Futex landing page shall use the Rodmena design system: dark theme with violet-to-pink gradient accents, Inter font, glassmorphism cards, and the signature slash brand element.\n- LX-2: The landing page shall include a fixed navbar with Futex branding and navigation links consistent with the Rodmena company site layout.\n- LX-3: The landing page shall include a hero section explaining Futex as a human-in-the-loop control plane with gradient headline and CTA buttons.\n- LX-4: The landing page shall present features as a responsive grid of glassmorphism cards with gradient icon headers.\n- LX-5: The landing page shall include an architecture/code-example section and a footer matching the Rodmena site structure.\n- LX-6: The change shall be committed to main and deployed (restart api service).