Music on iPhone: keep 3-5 songs ready (size-capped), skip a song that will not load instead of sticking on Buffering, tidy the album buttons, lock-screen art in more sizes, and accept the lookups and song-cache settings on the server

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaC9HmtHMdRP8dAbN4wAKj

tools/settingskeys-test.js

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+// Every setting the app syncs must be one the server accepts, or the whole save fails.
+const fs = require('fs'), assert = require('assert');
+const client = fs.readFileSync(__dirname + '/../public/app.js', 'utf8'), server = fs.readFileSync(__dirname + '/../settings.js', 'utf8');
+const list = s => [...s.matchAll(/'([a-z_]+)'/g)].map(m => m[1]);
+const c = list(/const SYNCED = new Set\(\[([^\]]*)\]/.exec(client)[1]), s = new Set(list(/const KEYS = new Set\(\[([^\]]*)\]/.exec(server)[1]));
+const missing = c.filter(k => !s.has(k)); assert.deepStrictEqual(missing, [], 'the server would refuse: ' + missing.join(', '));
+console.log('settings keys: ' + c.length + ' synced settings, all accepted by the server');