Add mock API and reorg code for clarity

src/view/screens/Home.tsx

@@ -0,0 +1,21 @@
+import React from 'react'
+import {Text, Button, View} from 'react-native'
+import {Shell} from '../shell'
+import type {RootTabsScreenProps} from '../routes/types'
+import {useStores} from '../../state'
+
+export function Home({navigation}: RootTabsScreenProps<'Home'>) {
+  const store = useStores()
+  return (
+    <Shell>
+      <View style={{alignItems: 'center'}}>
+        <Text style={{fontSize: 20, fontWeight: 'bold'}}>Home</Text>
+        <Button
+          title="Go to Jane's profile"
+          onPress={() => navigation.navigate('Profile', {name: 'Jane'})}
+        />
+        <Button title="Logout" onPress={() => store.session.logout()} />
+      </View>
+    </Shell>
+  )
+}