batch add students: add optional group selection in batch modal

public/login.html

@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html lang="ru">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<title>Вход — Админ-панель</title>
+<style>
+*{margin:0;padding:0;box-sizing:border-box}
+:root{--bg:#f5f5f5;--card:#fff;--border:#e5e5e5;--accent:#2563eb;--text:#171717;--muted:#737373;--radius:12px}
+body{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;background:var(--bg);color:var(--text);min-height:100dvh;display:flex;align-items:center;justify-content:center}
+.login{max-width:320px;width:100%;text-align:center;background:var(--card);border:1px solid var(--border);border-radius:16px;padding:40px 32px}
+.login h1{font-size:1.3rem;font-weight:600;margin-bottom:24px}
+.login input{width:100%;background:var(--bg);border:1px solid var(--border);color:var(--text);border-radius:var(--radius);padding:14px 16px;font-size:.95rem;outline:none;margin-bottom:12px;text-align:center}
+.login input:focus{border-color:var(--accent)}
+.login button{width:100%;background:var(--accent);color:#fff;border:none;border-radius:var(--radius);padding:14px;font-size:1rem;font-weight:600;cursor:pointer}
+.login button:hover{opacity:.85}
+.login .err{color:#ef4444;font-size:.85rem;margin-top:8px;display:none}
+.login .back{margin-top:16px}
+.login .back a{color:var(--muted);text-decoration:none;font-size:.8rem}
+.login .back a:hover{color:var(--text)}
+</style>
+</head>
+<body>
+<div class="login">
+  <h1>Админ-панель</h1>
+  <input type="password" id="pwdInput" placeholder="Пароль" autofocus>
+  <button onclick="doLogin()">Войти</button>
+  <div class="err" id="loginErr">Неверный пароль</div>
+  <div class="back"><a href="/">На главную</a></div>
+</div>
+<script>
+const API = location.origin;
+document.getElementById('pwdInput').addEventListener('keydown', e => { if (e.key === 'Enter') doLogin(); });
+
+async function doLogin() {
+  const pwd = document.getElementById('pwdInput').value;
+  if (!pwd) return;
+  try {
+    const res = await fetch(`${API}/api/stats`, { headers: { 'X-Admin-Token': pwd } });
+    if (res.ok) {
+      sessionStorage.setItem('adminToken', pwd);
+      location.href = 'dashboard.html';
+    } else {
+      document.getElementById('loginErr').style.display = 'block';
+    }
+  } catch {
+    document.getElementById('loginErr').style.display = 'block';
+  }
+}
+</script>
+</body>
+</html>