Add landing page for voicebox.sh

- Created a new landing page using Next.js 16, featuring a modern design with Tailwind CSS.
- Implemented essential components including Header, Footer, and DownloadSection for user navigation and download options.
- Configured Tailwind CSS and PostCSS for styling, and set up TypeScript for type safety.
- Added a README with setup instructions, project structure, and deployment guidelines.
- Integrated GitHub links for easy access to the repository and releases.
- Established a consistent UI with reusable components and responsive design.

landing/src/components/Header.tsx

@@ -0,0 +1,46 @@
+'use client';
+
+import Link from 'next/link';
+import { Github } from 'lucide-react';
+import { Button } from '@/components/ui/button';
+import { GITHUB_REPO } from '@/lib/constants';
+
+export function Header() {
+  return (
+    <header className="border-b border-border bg-background/80 backdrop-blur-xl sticky top-0 z-50">
+      <div className="container mx-auto px-4">
+        <div className="flex items-center justify-between h-16">
+          {/* Logo */}
+          <Link href="/" className="flex items-center gap-2 font-bold text-xl sm:text-2xl hover:opacity-80 transition-opacity">
+            voicebox
+          </Link>
+
+          {/* Actions */}
+          <div className="flex items-center gap-2 sm:gap-4">
+            <Button
+              variant="outline"
+              size="sm"
+              asChild
+              className="hidden sm:flex"
+            >
+              <a href={GITHUB_REPO} target="_blank" rel="noopener noreferrer">
+                <Github className="h-4 w-4 mr-2" />
+                GitHub
+              </a>
+            </Button>
+            <Button
+              variant="ghost"
+              size="icon"
+              asChild
+              className="sm:hidden"
+            >
+              <a href={GITHUB_REPO} target="_blank" rel="noopener noreferrer" aria-label="GitHub">
+                <Github className="h-5 w-5" />
+              </a>
+            </Button>
+          </div>
+        </div>
+      </div>
+    </header>
+  );
+}