Apply Stability Nexus brand theme and accent colors to UI components

Summary

Apply the brand accent colors (amber/gold and green) defined in issue #15 to the main UI components (Navbar, Hero, Features, and Footer) to add visual depth and color to the black-and-white theme.

Tasks

• Navbar: Enhance the logo 'W' with a brand amber glow/ring or background accent.
• Hero Section:
  • Change ambient soft glow spots from grey to soft brand-amber and brand-green gradients.
  • Highlight key heading words with a gradient using brand-amber and neutral-800.
  • Use brand-amber for the ⚡ MATCH icon and connection line in the visual mock panel.
• Features Section:
  • Update feature card icons to use brand accent colors (e.g., brand-green, brand-amber, blue).
  • Add soft brand-colored glow/highlights on hovering feature cards.
• CTA Section & Footer: Apply brand-amber highlights/CTAs to make the primary actions stand out.

Files to change

• components/layout/Navbar.tsx (~15 lines changed)
• components/landing/HeroSection.tsx (~30 lines changed)
• components/landing/FeaturesSection.tsx (~25 lines changed)
• components/landing/CTASection.tsx (~15 lines changed)

Acceptance criteria

• Visual design is elevated from pure black-and-white with elegant brand accent highlights
• Maintain premium look without cluttering the screen
• npm run build succeeds