feat(#79): Add rate limiting to contact page form

src/lib/utils/rateLimiter.ts

@@ -0,0 +1,30 @@
+type RateLimitStore = {
+	[key: string]: { count: number; lastRequest: number };
+};
+
+const rateLimitStore: RateLimitStore = {};
+const RATE_LIMIT_WINDOW = 60 * 5000; // 5 minutes
+const MAX_REQUESTS = 5;
+
+export function isRateLimited(ip: string): boolean {
+	const currentTime = Date.now();
+	const requestInfo = rateLimitStore[ip];
+
+	if (!requestInfo) {
+		rateLimitStore[ip] = { count: 1, lastRequest: currentTime };
+		return false;
+	}
+
+	if (currentTime - requestInfo.lastRequest > RATE_LIMIT_WINDOW) {
+		rateLimitStore[ip] = { count: 1, lastRequest: currentTime };
+		return false;
+	}
+
+	if (requestInfo.count >= MAX_REQUESTS) {
+		return true;
+	}
+
+	rateLimitStore[ip].count += 1;
+	rateLimitStore[ip].lastRequest = currentTime;
+	return false;
+}