Add theme toggle, hero snippet, and reorganize homepage components

- Set up next-themes with a light/dark toggle in the header and move all
  sections onto theme tokens; dark mode stays pure black
- Replace the hero terminal line with the AI Elements Snippet component
- Restructure components into layout/, sections/, and shared/ with
  site-wide config in lib/site.ts

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

lib/site.ts

@@ -0,0 +1,53 @@
+export const siteConfig = {
+  name: 'Vertex',
+  title: 'Vertex — Build. Preview. Ship.',
+  description:
+    'Vertex gives frontend teams the tooling and cloud infrastructure to build, preview, and ship a faster web.',
+  tagline: 'The frontend cloud for teams that ship.',
+  links: {
+    github: 'https://github.com',
+    twitter: 'https://x.com',
+    login: '#',
+    signup: '#',
+  },
+};
+
+export type NavigationItem = {
+  label: string;
+  href: string;
+  description: string;
+};
+
+export const navigationItems: NavigationItem[] = [
+  { label: 'Products', href: '#', description: 'Everything you need to ship' },
+  { label: 'Solutions', href: '#', description: 'Built for teams of every size' },
+  { label: 'Resources', href: '#', description: 'Guides, templates, and changelog' },
+  { label: 'Docs', href: '#', description: 'Your first deploy starts here' },
+  { label: 'Pricing', href: '#', description: 'Start free. Scale at your pace.' },
+];
+
+export type FooterColumn = {
+  heading: string;
+  links: { label: string; href: string }[];
+};
+
+const link = (label: string, href = '#') => ({ label, href });
+
+export const footerColumns: FooterColumn[] = [
+  {
+    heading: 'Products',
+    links: ['Previews', 'Edge Network', 'Analytics', 'Storage', 'Firewall'].map((l) => link(l)),
+  },
+  {
+    heading: 'Resources',
+    links: ['Docs', 'Guides', 'Changelog', 'Templates', 'Status'].map((l) => link(l)),
+  },
+  {
+    heading: 'Company',
+    links: ['About', 'Careers', 'Blog', 'Customers', 'Contact'].map((l) => link(l)),
+  },
+  {
+    heading: 'Legal',
+    links: ['Privacy', 'Terms', 'Security', 'DPA', 'Cookies'].map((l) => link(l)),
+  },
+];