feat(compliance): add GDPR/RODO compliant cookie consent banner

Implemented cookie consent banner to comply with EU regulations (GDPR/RODO).
The banner appears on first visit and stores user preference in localStorage.

Features:
- Non-intrusive bottom banner with clear messaging
- Accept/Decline options for user choice
- Link to privacy policy in About Us page
- Responsive design for mobile and desktop
- Auto-dismisses after consent with 1s delay on first show
- High z-index to stay above all content

Also added comprehensive Privacy & Cookies section to About Us page
explaining:
- What cookies we use (essential, analytics, preferences)
- How we handle user data
- GDPR/RODO compliance statements
- Contact information for privacy questions

Changes:
- Created CookieConsent component with modern UI
- Integrated banner into App.jsx
- Updated about-us.md with privacy policy section

frontend/src/components/common/CookieConsent.jsx

@@ -0,0 +1,85 @@
+import { useState, useEffect } from 'react';
+import { Cookie, X } from 'lucide-react';
+
+/**
+ * GDPR/RODO compliant cookie consent banner
+ * Shows at bottom of screen on first visit, stores consent in localStorage
+ */
+const CookieConsent = () => {
+  const [isVisible, setIsVisible] = useState(false);
+
+  useEffect(() => {
+    // Check if user has already consented
+    const hasConsented = localStorage.getItem('cookieConsent');
+    if (!hasConsented) {
+      // Show banner after a short delay for better UX
+      setTimeout(() => setIsVisible(true), 1000);
+    }
+  }, []);
+
+  const handleAccept = () => {
+    localStorage.setItem('cookieConsent', 'accepted');
+    setIsVisible(false);
+  };
+
+  const handleDecline = () => {
+    localStorage.setItem('cookieConsent', 'declined');
+    setIsVisible(false);
+  };
+
+  if (!isVisible) return null;
+
+  return (
+    <div className="fixed bottom-0 left-0 right-0 z-[9999] p-4 bg-gradient-to-t from-black/10 to-transparent pointer-events-none">
+      <div className="max-w-7xl mx-auto pointer-events-auto">
+        <div className="bg-white rounded-lg shadow-2xl border border-gray-200 p-4 sm:p-6">
+          <div className="flex flex-col sm:flex-row items-start sm:items-center gap-4">
+            {/* Icon */}
+            <div className="flex-shrink-0">
+              <div className="w-12 h-12 bg-primary-100 rounded-full flex items-center justify-center">
+                <Cookie className="w-6 h-6 text-primary-600" />
+              </div>
+            </div>
+
+            {/* Content */}
+            <div className="flex-1 min-w-0">
+              <h3 className="text-lg font-semibold text-gray-900 mb-1">
+                We use cookies
+              </h3>
+              <p className="text-sm text-gray-600">
+                We use cookies and similar technologies to enhance your experience, analyze site traffic,
+                and for authentication purposes. By clicking "Accept", you consent to our use of cookies.{' '}
+                <a
+                  href="/about-us"
+                  className="text-primary-600 hover:text-primary-700 underline"
+                  target="_blank"
+                  rel="noopener noreferrer"
+                >
+                  Learn more
+                </a>
+              </p>
+            </div>
+
+            {/* Actions */}
+            <div className="flex items-center gap-2 flex-shrink-0 w-full sm:w-auto">
+              <button
+                onClick={handleDecline}
+                className="flex-1 sm:flex-none px-4 py-2 text-sm font-medium text-gray-700 bg-gray-100 hover:bg-gray-200 rounded-lg transition-colors"
+              >
+                Decline
+              </button>
+              <button
+                onClick={handleAccept}
+                className="flex-1 sm:flex-none px-4 py-2 text-sm font-medium text-white bg-primary-600 hover:bg-primary-700 rounded-lg transition-colors"
+              >
+                Accept
+              </button>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+};
+
+export default CookieConsent;