feat: contain mobile Search focus through Preview (Closes #1390)

frontend/index.html

@@ -780,7 +780,7 @@
   </section>
 </div>
 
-<div id="cmd-palette" role="dialog" aria-label="Command palette">
+<div id="cmd-palette" role="dialog" aria-modal="true" aria-label="Command palette">
   <div class="cmd-palette-header">
     <strong>Search work</strong>
     <div class="cmd-palette-header-actions">
@@ -2367,6 +2367,7 @@
 <script src="static/device-storage.js"></script>
 <script src="static/mobile-device-setup.js"></script>
 <script src="static/mobile-search-viewport.js"></script>
+<script src="static/mobile-search-modal.js"></script>
 <script src="static/mobile-composer-viewport.js"></script>
 <script src="static/mention-composer.js"></script>
 <script src="static/push-notifications.js"></script>