Split app.js into one script per feature; versioning covers every public file; README for the new features

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/boot.js

@@ -0,0 +1,35 @@
+'use strict';
+// ---- Boot
+(async () => {
+  try { cfg = { ...cfg, ...(await (await fetch('/api/config')).json()) }; } catch {}
+  const loadedBuild = cfg.build;
+  // When a new version is deployed, an open page keeps running the old one. Tell the person, and offer a reload.
+  const checkForUpdate = async () => {
+    try {
+      const c = await (await fetch('/api/config', { cache: 'no-store' })).json();
+      if (c.build && loadedBuild && c.build !== loadedBuild && !document.getElementById('upd')) {
+        const b = document.createElement('div'); b.id = 'upd';
+        b.innerHTML = 'A new version of NE Hub is available. <button class="btn" id="updgo">Reload</button>';
+        document.body.appendChild(b); document.getElementById('updgo').onclick = () => location.reload();
+      }
+    } catch {}
+  };
+  document.addEventListener('visibilitychange', () => { if (document.visibilityState === 'visible') checkForUpdate(); });
+  setInterval(checkForUpdate, 10 * 60e3);
+  await loadMe();
+  await loadSettings();
+  sgStart();
+  addEventListener('hashchange', route);
+  restorePlayer();
+  route();
+  if ('serviceWorker' in navigator) navigator.serviceWorker.register('/sw.js').catch(() => {});
+})();
+
+// Keyboard (desktop): space play/pause, arrows seek, N/P next/previous.
+addEventListener('keydown', e => {
+  const tag = e.target.tagName || '', k = e.key;
+  if (e.metaKey || e.ctrlKey || e.altKey || !cur() || /^(INPUT|TEXTAREA|SELECT)$/.test(tag) || (k === ' ' && /^(BUTTON|A)$/.test(tag))) return;
+  if (k === ' ') { e.preventDefault(); toggle(); }
+  else if (k === 'ArrowRight') pl.a.currentTime += 10; else if (k === 'ArrowLeft') pl.a.currentTime = Math.max(0, pl.a.currentTime - 10);
+  else if (k === 'n' || k === 'N') next(); else if (k === 'p' || k === 'P') prev();
+});