feat: add client-side rate limiting to contact form

- Added `useRateLimit` hook
- Integrated hook into `Contact.tsx`
- Added translations for rate limit error
- Added unit tests
- Fixed type error in `Button.tsx` to allow build to pass

src/hooks/useRateLimit.ts

@@ -0,0 +1,38 @@
+import { useState, useCallback } from 'react';
+
+interface UseRateLimitReturn {
+  checkRateLimit: () => boolean;
+  remainingTime: number;
+}
+
+export function useRateLimit(key: string, cooldownMs: number): UseRateLimitReturn {
+  const [remainingTime, setRemainingTime] = useState(0);
+
+  const checkRateLimit = useCallback(() => {
+    try {
+      const now = Date.now();
+      const lastAttempt = localStorage.getItem(key);
+
+      if (lastAttempt) {
+        const lastTime = parseInt(lastAttempt, 10);
+        const timePassed = now - lastTime;
+
+        if (timePassed < cooldownMs) {
+          const remaining = Math.ceil((cooldownMs - timePassed) / 1000);
+          setRemainingTime(remaining);
+          return false;
+        }
+      }
+
+      localStorage.setItem(key, now.toString());
+      setRemainingTime(0);
+      return true;
+    } catch (error) {
+      console.warn('LocalStorage not available:', error);
+      // Fail safe: allow action if storage fails
+      return true;
+    }
+  }, [key, cooldownMs]);
+
+  return { checkRateLimit, remainingTime };
+}