android: the library's file stats on the cards, the artist's own plays, the thumbnail prewarm

The desktop Library's per-record file stats on the phone (library_album_stats,
one call for the whole library): FLAC 24/96 or MP3 320k badges on the cards,
the size on the list rows and the record page. The artist page's own
listening (artist_play_stats): the time played as a chip, the most played
track under "On this phone". The whole-library thumbnail warm a moment after
boot, at the cards' edge, one decode at a time behind the tiles' gate.

src/mobile/lib.svelte.js

@@ -9,6 +9,8 @@ export const lib = $state({
     recents: [],    // library rows only, with an album_id
     follows: [],
     playlists: [],
+    /** album id → { secs, bytes, avg_kbps, bit_depth, sample_rate, formats, last_played_at } — the desktop's library_album_stats */
+    stats: {},
     version: "",
     username: null,
     loaded: false,
@@ -104,6 +106,7 @@ export async function watchLibrary() {
             timer = setTimeout(async () => {
                 try { lib.albums = await api.libraryAlbums(); } catch { /* keep */ }
                 await refreshRecents();
+                void refreshStats();
             }, 600);
         });
         /* a playlist mutation (the desktop's commands emit it) re-lists them */
@@ -122,6 +125,24 @@ export async function loadLibrary() {
     try { lib.follows = (await api.followedArtists()) || []; } catch { lib.follows = []; }
     try { lib.playlists = (await api.listPlaylists()) || []; } catch { lib.playlists = []; }
     lib.loaded = true;
+    void refreshStats();
+}
+
+/** The files' own aggregates per record — one call for the whole library
+ *  (the desktop's RECENTS_FLOOR_SECS, 45, is the floor a play must reach
+ *  to count as the last one). */
+export async function refreshStats() {
+    try {
+        const rows = (await api.libraryAlbumStats(45)) || [];
+        lib.stats = Object.fromEntries(rows.map((r) => [r.album_id, r]));
+    } catch { /* the cards stay quiet */ }
+}
+/** "FLAC 24/96" for a lossless record, "MP3 320k" for a lossy one. */
+export function statLabel(st) {
+    if (!st || !st.formats?.length) return "";
+    const f = String(st.formats[0]).toUpperCase();
+    if (st.bit_depth && st.sample_rate) return f + " " + st.bit_depth + "/" + (st.sample_rate % 1000 === 0 ? st.sample_rate / 1000 : (st.sample_rate / 1000).toFixed(1));
+    return st.avg_kbps ? f + " " + st.avg_kbps + "k" : f;
 }
 
 export async function refreshPlaylists() {