feat: Implement mobile application and lead processing utilities.

innungsapp/apps/mobile/components/ui/LoadingSpinner.tsx

@@ -0,0 +1,9 @@
+import { View, ActivityIndicator } from 'react-native'
+
+export function LoadingSpinner() {
+  return (
+    <View className="flex-1 items-center justify-center">
+      <ActivityIndicator size="large" color="#003B7E" />
+    </View>
+  )
+}