feat(popup): add email capture popup with Mautic integration

- Email capture popup with scroll (10%) and exit intent triggers
- First name field and full tracking (UTM, device, time on page)
- Mautic API integration for contact creation
- GeoIP detection for country/region
- 4 locale support (sr, en, de, fr)
- Mautic tracking script in layout

src/components/providers/AnalyticsProvider.tsx

@@ -9,5 +9,5 @@ interface AnalyticsProviderProps {
 
 export default function AnalyticsProvider({ clientId }: AnalyticsProviderProps) {
   // No-op component - Rybbit is loaded via next/script in layout.tsx
-  return null;
+  return <></>;
 }