add upstash rate limiting

apps/web/src/lib/rate-limit.ts

@@ -0,0 +1,14 @@
+// lib/rate-limit.ts
+import { Ratelimit } from "@upstash/ratelimit";
+import { Redis } from "@upstash/redis";
+
+const redis = new Redis({
+  url: process.env.UPSTASH_REDIS_REST_URL!,
+  token: process.env.UPSTASH_REDIS_REST_TOKEN!,
+});
+
+export const waitlistRateLimit = new Ratelimit({
+  redis,
+  limiter: Ratelimit.slidingWindow(5, "1 m"), // 5 requests per minute
+  analytics: true,
+});