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>

components/shared/action-buttons.tsx

@@ -0,0 +1,41 @@
+import { Button } from '@/components/ui/button';
+import { cn } from '@/lib/utils';
+
+type Action = { label: string; href: string };
+
+export function ActionButtons({
+  primary,
+  secondary,
+  className,
+}: {
+  primary: Action;
+  secondary?: Action;
+  className?: string;
+}) {
+  return (
+    <div
+      className={cn(
+        'flex flex-col items-center justify-center gap-3 sm:flex-row',
+        className,
+      )}
+    >
+      <Button
+        asChild
+        size="lg"
+        className="h-11 rounded-full bg-foreground px-6 text-[15px] text-background hover:bg-foreground/90"
+      >
+        <a href={primary.href}>{primary.label}</a>
+      </Button>
+      {secondary && (
+        <Button
+          asChild
+          size="lg"
+          variant="outline"
+          className="h-11 rounded-full border-foreground/20 bg-transparent px-6 text-[15px] text-foreground hover:bg-foreground/5 hover:text-foreground"
+        >
+          <a href={secondary.href}>{secondary.label}</a>
+        </Button>
+      )}
+    </div>
+  );
+}

components/shared/brand.tsx

@@ -0,0 +1,20 @@
+import { cn } from '@/lib/utils';
+import { siteConfig } from '@/lib/site';
+
+export function Brand({ className }: { className?: string }) {
+  return (
+    <span className={cn('flex items-center gap-2 font-medium', className)}>
+      <svg
+        width="22"
+        height="22"
+        viewBox="0 0 24 24"
+        fill="none"
+        aria-hidden="true"
+        className="shrink-0"
+      >
+        <path d="M12 2L23 21H1L12 2Z" fill="currentColor" />
+      </svg>
+      <span className="text-[17px] tracking-tight">{siteConfig.name}</span>
+    </span>
+  );
+}

components/shared/container.tsx

@@ -0,0 +1,9 @@
+import { type ComponentProps } from 'react';
+
+import { cn } from '@/lib/utils';
+
+export function Container({ className, ...props }: ComponentProps<'div'>) {
+  return (
+    <div className={cn('mx-auto w-full max-w-6xl px-6', className)} {...props} />
+  );
+}

components/shared/gradient-glow.tsx

@@ -0,0 +1,21 @@
+import { cn } from '@/lib/utils';
+
+/**
+ * Soft conic-gradient bloom used behind hero and CTA copy.
+ * Position and size it with `className`; it never captures pointer events.
+ */
+export function GradientGlow({ className }: { className?: string }) {
+  return (
+    <div
+      aria-hidden="true"
+      className={cn(
+        'pointer-events-none absolute rounded-full blur-3xl',
+        className,
+      )}
+      style={{
+        background:
+          'conic-gradient(from 180deg at 50% 50%, #7c3aed, #2563eb, #06b6d4, #ec4899, #7c3aed)',
+      }}
+    />
+  );
+}

components/shared/section-heading.tsx

@@ -0,0 +1,44 @@
+import { cn } from '@/lib/utils';
+
+export function SectionHeading({
+  eyebrow,
+  title,
+  description,
+  align = 'left',
+  className,
+}: {
+  eyebrow?: string;
+  title: string;
+  description?: string;
+  align?: 'left' | 'center';
+  className?: string;
+}) {
+  return (
+    <div
+      className={cn(
+        'max-w-2xl',
+        align === 'center' && 'mx-auto text-center',
+        className,
+      )}
+    >
+      {eyebrow && (
+        <p className="font-mono text-xs uppercase tracking-[0.2em] text-foreground/40">
+          {eyebrow}
+        </p>
+      )}
+      <h2
+        className={cn(
+          'text-3xl font-semibold tracking-tight sm:text-4xl',
+          eyebrow && 'mt-4',
+        )}
+      >
+        {title}
+      </h2>
+      {description && (
+        <p className="mt-5 text-lg leading-8 text-foreground/55">
+          {description}
+        </p>
+      )}
+    </div>
+  );
+}