Compact HE-AAC audio saves: server lane with fdkaac, shrink saved songs from Saved videos

frontend/autosave.test.js

@@ -16,7 +16,7 @@ function harness({ autoPreload = true, cached = [], result = { ok: true, cached:
     SaveSlots: { acquire: async () => {}, release() {} },
     SaveQueue: { add: v => jobs.set(v.id, { status: 'queued' }), remove: id => jobs.delete(id), progress() {}, state: (id, status, message) => jobs.set(id, { status, message }) },
     API: { cacheDownload: async id => { calls.push(id); if (error) throw error; return result; } },
-    recordDeviceFile() {}, saveStillArt: async () => false, warmThumb() {}, thumbUrlFor: () => '', cacheMutations: 0,
+    recordDeviceFile() {}, saveStillArt: async () => false, CompactSaves: { mark() {}, drop() {} }, warmThumb() {}, thumbUrlFor: () => '', cacheMutations: 0,
   });
   const preload = source.slice(source.indexOf('async function preload(video,'), source.indexOf('// A device copy that failed to play.'));
   const playlists = source.slice(source.indexOf('function preloadPlaylist(pl)'), source.indexOf('// Update a single card\'s saved badge'));