Add the on-device IndexedDB file registry and hash saves while downloading

frontend/index.html

@@ -562,6 +562,7 @@
     <script src="lyrics-core.js"></script>
     <script src="stats-core.js"></script>
     <script src="sha256.js"></script>
+    <script src="device-db.js"></script>
     <script src="async-guard.js"></script>
     <script src="sw-update.js"></script>
     <script src="app.js"></script>