feat(web): persist browser state

Keep settings, aliases, and recent drawings across browser sessions.

Load Start-page videos from a Pages-generated snapshot.

index.html

@@ -47,6 +47,7 @@
     <link data-trunk rel="copy-dir" href="web/fonts" />
     <link data-trunk rel="copy-file" href="web/ocs-parse-worker.js" />
     <link data-trunk rel="copy-file" href="web/discussions.json" />
+    <link data-trunk rel="copy-file" href="web/videos.json" />
   </head>
   <body>
     <div id="loading">