feat: restructure client-side code

src/server/game/deck.js

@@ -0,0 +1,18 @@
+import fs from 'fs';
+import path from 'path';
+import { parseFile as mmParseFile } from 'music-metadata';
+import { DATA_DIR } from '../config.js';
+import { loadYearsIndex } from '../years.js';
+import { shuffle } from './state.js';
+
+export async function loadDeck() {
+  const years = loadYearsIndex();
+  const files = fs.readdirSync(DATA_DIR).filter((f) => /\.(mp3|wav|m4a|ogg)$/i.test(f));
+  const tracks = await Promise.all(files.map(async (f) => {
+    const fp = path.join(DATA_DIR, f);
+    let year = null, title = path.parse(f).name, artist = '';
+    try { const meta = await mmParseFile(fp, { duration: false }); title = meta.common.title || title; artist = meta.common.artist || artist; year = meta.common.year || null; } catch {}
+    const y = years[f]?.year ?? year; return { id: f, file: f, title, artist, year: y };
+  }));
+  return shuffle(tracks);
+}