batch add students: add optional group selection in batch modal

public/dashboard.html

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html lang="ru">
+<head>
+<meta charset="UTF-8">
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<title>Дашборд — Админ-панель</title>
+<link rel="stylesheet" href="admin.css">
+</head>
+<body data-page="dashboard">
+<div class="layout">
+  <div class="sidebar" id="sidebar"></div>
+  <div class="main">
+    <h2>Дашборд</h2>
+    <div class="stats" id="stats"></div>
+  </div>
+</div>
+<div class="toast" id="toast"></div>
+<script src="admin.js"></script>
+<script>
+async function loadDashboard() {
+  const res = await fetch(`${API}/api/stats`, { headers: hdr() });
+  const s = await res.json();
+  document.getElementById('stats').innerHTML = `
+    <div class="stat"><div class="num">${s.entries}</div><div class="label">Всего записей</div></div>
+    <div class="stat"><div class="num">${s.students}</div><div class="label">Студентов</div></div>
+    <div class="stat"><div class="num">${s.groups}</div><div class="label">Групп</div></div>
+    <div class="stat"><div class="num">${s.today}</div><div class="label">Сегодня</div></div>
+  `;
+}
+
+(async () => {
+  if (await checkAuth()) {
+    buildSidebar(document.body.dataset.page);
+    loadDashboard();
+  }
+})();
+</script>
+</body>
+</html>