Added "Services" page & refactor layout structure

- Introduced a new Services component with basic setup.
- Updated layout files to ensure consistent global styling references.
- Enhanced Navbar with pathname detection for active link styling.
- Fixed navigation link URL for "Leistungen" in constants.

app/services/page.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import Contact from "@/components/Contact/Contact";
+
+const ContactPage = () => {
+    return (
+        <div>
+            <Contact/>
+        </div>
+    );
+};
+
+export default ContactPage;