android: hours on the library's count line, By format, Jump back in on the empty search

The desktop Library summary's hours on the phone's count line; a By format
order from the file stats (lossless by depth and rate first, then by
bitrate, the badge as the card's line); the empty Search page's Jump back
in — the last records played — as the desktop's empty search shows them.

src/lib/mockLibrary.js

@@ -325,7 +325,7 @@ export function mockInvoke(cmd, args) {
     if (cmd === "app_status") return Promise.resolve({ version: "mock", connected_as: null });
     if (cmd === "library_albums") return Promise.resolve(albums);
     if (cmd === "library_album_stats") return Promise.resolve(albums.map(statsFor));
-    if (cmd === "recent_albums") return Promise.resolve([]);
+    if (cmd === "recent_albums") return Promise.resolve(albums.slice(0, 3).map((a, i) => ({ kind: "library", album_id: a.id, title: a.title, artist: a.artist, art_path: a.art_path, last_played_at: Math.floor(Date.now() / 1000) - 3600 * (i + 1) })));
     if (cmd === "album_tracks")
         return new Promise((r) => setTimeout(() => r(tracksFor(args.albumId)), 60));
     if (cmd === "album_art") {