[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/view/shell/bottom-bar/BottomBarStyles.tsx

@@ -1,4 +1,5 @@
 import {StyleSheet} from 'react-native'
+
 import {colors} from 'lib/styles'
 
 export const styles = StyleSheet.create({
@@ -65,6 +66,9 @@ export const styles = StyleSheet.create({
   profileIcon: {
     top: -4,
   },
+  messagesIcon: {
+    top: 2,
+  },
   onProfile: {
     borderWidth: 1,
     borderRadius: 100,