Add onboarding screen + token check

app/index.tsx

@@ -0,0 +1,31 @@
+import {Redirect, Stack} from 'expo-router';
+import {StyleSheet, Text, TextInput, TouchableOpacity} from 'react-native';
+
+import {ThemedText} from '@/components/ThemedText';
+import {ThemedView} from '@/components/ThemedView';
+import {useToken} from '@/context/AppProvider';
+import {Colors} from '@/constants/Colors';
+import React, {useEffect} from 'react';
+import {useColorScheme} from '@/hooks/useColorScheme';
+import {Message} from '@/services/message';
+import {Request} from '@/services/request';
+import { router } from 'expo-router';
+
+export default function OnboardStartScreen() {
+  const {token, isLoading} = useToken();
+
+  // You can keep the splash screen open, or render a loading screen like we do here.
+  if (isLoading) {
+    return (
+      <ThemedView>
+        <ThemedText>Laden...</ThemedText>
+      </ThemedView>
+    );
+  }
+
+  if (!token) {
+    return <Redirect href="/(onboarding)/start"/>;
+  }
+
+  return <Redirect href="/(tabs)"/>;
+}