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>

server.js

@@ -100,7 +100,7 @@ function serveStatic(req, res) {
     if (err) { res.writeHead(404); return res.end('Not found'); }
     // The pages link to /app.js?v=<build> etc. A new release changes the address, so no proxy cache ("Cache Assets" in
     // Nginx Proxy Manager, a CDN, the browser) can hand out an old copy.
-    if (p === '/index.html' || p === '/login.html') data = Buffer.from(String(data).replace(/(src|href)="(\/(?:app|webauthn|login|links|palette|shell|calendar-views|music-extras|file-history|reminders)\.js|\/style\.css)"/g, `$1="$2?v=${BUILD}"`));
+    if (p === '/index.html' || p === '/login.html') data = Buffer.from(String(data).replace(/(src|href)="(\/[\w-]+\.js|\/style\.css)"/g, `$1="$2?v=${BUILD}"`));
     const headers = { 'content-type': TYPES[path.extname(file)] || 'application/octet-stream' };
     if (p.startsWith('/icons/')) headers['cache-control'] = 'public, max-age=604800'; // icons and splash screens rarely change
     else { // everything else: the browser may keep a copy but must check with us first, so a new version is never missed
@@ -114,7 +114,7 @@ function serveStatic(req, res) {
 }
 
 // Changes whenever the app's files change, so an open page can tell that a newer version is available.
-const BUILD = (() => { try { return crypto.createHash('sha1').update(['app.js', 'links.js', 'palette.js', 'shell.js', 'calendar-views.js', 'music-extras.js', 'file-history.js', 'reminders.js', 'index.html', 'style.css', 'webauthn.js', 'login.js', 'login.html', 'sw.js'].map(f => fs.readFileSync(path.join(PUBLIC, f))).join('')).digest('hex').slice(0, 12); } catch { return String(Date.now()); } })();
+const BUILD = (() => { try { return crypto.createHash('sha1').update(fs.readdirSync(PUBLIC).filter(f => /\.(js|css|html)$/.test(f)).sort().map(f => fs.readFileSync(path.join(PUBLIC, f))).join('')).digest('hex').slice(0, 12); } catch { return String(Date.now()); } })();
 
 // ---- OnlyOffice in-app editing (JWT-signed editor config + save-back callback to Seafile)
 const JWT_SECRET = process.env.ONLYOFFICE_JWT_SECRET || '';