feat(antispam): add server-side contact form spam guard (honeypot, time-trap, rate limit, link cap)

components/forms/ContactForm.tsx

@@ -7,6 +7,7 @@ import { sendContactFormAction } from '@/app/actions/contact';
 
 export function ContactForm() {
   const [status, setStatus] = React.useState<'idle' | 'loading' | 'success' | 'error'>('idle');
+  const [formLoadedAt] = React.useState(() => Date.now());
 
   const handleSubmit = async (e: React.FormEvent<HTMLFormElement>) => {
     e.preventDefault();
@@ -132,6 +133,7 @@ export function ContactForm() {
           </div>
 
           <input type="text" name="company_website" style={{ display: 'none' }} tabIndex={-1} autoComplete="off" />
+          <input type="hidden" name="form_loaded_at" value={formLoadedAt} />
 
           <Button 
             type="submit"