feat(web): scaffold Next.js 16 dashboard with design system and auth client (#82)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/web/src/lib/cn.ts

@@ -0,0 +1,7 @@
+import { clsx, type ClassValue } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+
+/** Merge and deduplicate Tailwind class names. */
+export function cn(...inputs: ClassValue[]): string {
+  return twMerge(clsx(inputs));
+}