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/auth-client.ts

@@ -0,0 +1,7 @@
+import { createAuthClient } from 'better-auth/react';
+
+export const authClient: ReturnType<typeof createAuthClient> = createAuthClient({
+  baseURL: process.env['NEXT_PUBLIC_GATEWAY_URL'] ?? 'http://localhost:4000',
+});
+
+export const { useSession, signIn, signUp, signOut } = authClient;