Add interactive map to Impressum with configurable coordinates

- Add OpenStreetMap iframe to legal page showing business location
- Support ADDRESS_LATITUDE and ADDRESS_LONGITUDE environment variables
- Generate dynamic map URLs based on configured coordinates
- Include link to full map view
- Update legal-config.ts interface to include latitude/longitude
- Document new environment variables in README.md
- Use Kiel coordinates as default (54.3233, 10.1228)

src/client/app.tsx

@@ -251,7 +251,7 @@ function App() {
       <footer className="bg-white border-t border-pink-100 mt-16">
         <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
           <div className="text-center text-gray-600">
-            <p>&copy; 2024 Stargirlnails Kiel. Professional nail care services.</p>
+            <p>&copy; 2025 Stargirlnails Kiel. Professional nail design & care with 🩷 and passion in Kiel 🌇.</p>
           </div>
         </div>
       </footer>