add basic model and interface

src/Tabs/messageTab.tsx

@@ -0,0 +1,15 @@
+import * as React from "bloatless-react";
+
+import { MessageComposer } from "../Views/messageComposer";
+import { ThreadView } from "../Views/threadView";
+import { translation } from "../translations";
+
+export function MessageTab() {
+  return (
+    <article id="message-tab">
+      <header>{translation.messages}</header>
+      {ThreadView()}
+      <footer>{MessageComposer()}</footer>
+    </article>
+  );
+}