fix(frontend): restore DOMContentLoaded wrapper in app.js and render login overlay by default

app/static/index.html

@@ -5,7 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
     <title>Notes — Персональный тренажер и словарь английского языка</title>
     <meta name="description" content="Защищённый персональный тренажёр и словарь английского языка с интервальными повторениями SRS SM-2, контекстным поиском и озвучкой">
-    <link rel="stylesheet" href="/static/css/style.css?v=2.9">
+    <link rel="stylesheet" href="/static/css/style.css?v=3.0">
     
     <!-- PWA meta and icons -->
     <link rel="manifest" href="/manifest.json">
@@ -18,7 +18,7 @@
 </head>
 <body>
     <!-- Login Overlay / Page -->
-    <div id="login-overlay" class="login-overlay hidden">
+    <div id="login-overlay" class="login-overlay">
         <div class="login-card">
             <div class="login-header">
                 <div class="login-logo">📖</div>
@@ -928,7 +928,7 @@
     <!-- Audio Element for native streaming -->
     <audio id="global-audio-player" preload="none"></audio>
 
-    <script src="/static/js/app.js?v=2.9"></script>
+    <script src="/static/js/app.js?v=3.0"></script>
 </body>
 </html>
 

app/static/js/app.js

@@ -1,7 +1,7 @@
 // Notes Application Frontend Logic - Complete SRS, Heatmap, Quiz, and Analytics
-    // Persistent session: auto-inject Authorization header if token exists in localStorage
+// Persistent session: auto-inject Authorization header if token exists in localStorage
-    const originalFetch = window.fetch;
+const originalFetch = window.fetch;
-    window.fetch = function(url, options = {}) {
+window.fetch = function(url, options = {}) {
     const token = localStorage.getItem('notes_token');
     if (token && typeof url === 'string' && url.startsWith('/api/')) {
         options.headers = options.headers || {};
@@ -20,8 +20,9 @@
         }
     }
     return originalFetch.call(this, url, options);
-    };
+};
 
+document.addEventListener('DOMContentLoaded', () => {
     // Register PWA Service Worker
     if ('serviceWorker' in navigator) {
         navigator.serviceWorker.register('/sw.js', { scope: '/' })