[Clipclops] New routes with placeholder screens (#3725)

* add new routes with placeholder screens

* gate content

* add filled envelope style

* swap filled state

* switch to `useAgent`

src/screens/Messages/gate.tsx

@@ -0,0 +1,17 @@
+import React from 'react'
+import {Text, View} from 'react-native'
+
+export function ClipClopGate() {
+  return (
+    <View
+      style={{
+        flex: 1,
+        alignItems: 'center',
+        justifyContent: 'center',
+        gap: 20,
+      }}>
+      <Text style={{fontSize: 50}}>🐴</Text>
+      <Text style={{textAlign: 'center'}}>Nice try</Text>
+    </View>
+  )
+}