feat: initial commit — asaas-checkout template white-label

Template genérico de checkout com ASAAS, parametrizado via env vars.
Inclui fluxo completo: checkout → pedido → polling → webhook → admin.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/ui/skeleton.tsx

@@ -0,0 +1,7 @@
+import { cn } from "@/lib/utils"
+
+function Skeleton({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) {
+  return <div className={cn("animate-pulse rounded-md bg-muted", className)} {...props} />
+}
+
+export { Skeleton }