feat: manage private device storage (Closes #998)

frontend/index.html

@@ -108,6 +108,17 @@
         </div>
       </li>
     </ol>
+    <section class="device-storage" aria-labelledby="device-storage-heading">
+      <div>
+        <h3 id="device-storage-heading">Private device storage</h3>
+        <p class="small" id="device-storage-summary" role="status" aria-live="polite">Checking private storage…</p>
+        <p class="small muted" id="device-storage-detail"></p>
+      </div>
+      <div class="device-storage-actions">
+        <button id="clear-device-caches" type="button">Clear cached copies</button>
+        <button id="clear-private-device-data" type="button">Clear all private data</button>
+      </div>
+    </section>
     <p id="device-setup-ready-status" class="device-setup-ready" role="status" aria-live="polite"></p>
   </section>
 </div>
@@ -1638,6 +1649,8 @@
 <script src="static/mobile-insights.js"></script>
 <script src="static/mobile-app-shortcuts.js"></script>
 <script src="static/install-app.js"></script>
+<script src="static/private-device-data.js"></script>
+<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-composer-viewport.js"></script>