UI rework: modal dialogs, inline lab editing, manual creation, content management

- Dashboard: real stats (groups, students, labs, average grade), labs/groups
  summary lists, no placeholder tile
- Lab page: view + edit combined — metadata form in modal, condition rendered
  as markdown, per-level variant tables with add/edit/delete dialogs,
  level rename/delete, student level/variant selectors with group filter
- Labs list: create-lab dialog with manual level entry (code; title lines)
- Groups: create-group dialog, add-student dialog (auto password, toast card)
- Content: public /learn reader is the single place; admin buttons (new
  article with chapter/section create-or-select, rename/delete chapters and
  sections, move articles between sections, import zip) appear for admins;
  removed separate 'Контент' admin section
- Buttons use btn classes instead of nav-link
- Favicon: generated SVG book icon
- Security: CSRF synchronizer token interceptor (replaced spring-security in
  web which broke logback under nested jars), session regenerated on login,
  hardened session cookie, gateway actuator limited to health,info
- Jackson 3: nullable-safe request DTOs for labs (FAIL_ON_NULL_FOR_PRIMITIVES)
- academic: POST /labs (manual create with levels), level add/rename/delete,
  content chapters/sections CRUD, article create/move/delete endpoints

web/src/main/resources/templates/admin/dashboard.html

@@ -4,24 +4,51 @@
 <body>
 <div id="content">
     <h1 class="page-title">Панель преподавателя</h1>
+
     <div class="grid grid-stats">
         <div class="card card-body"><p class="stat-title">Группы</p><p class="stat-value" th:text="${groupCount}">0</p></div>
         <div class="card card-body"><p class="stat-title">Студенты</p><p class="stat-value" th:text="${studentCount}">0</p></div>
-        <div class="card card-body"><p class="stat-title">Лабораторные</p><p class="stat-value text-muted">скоро</p></div>
+        <div class="card card-body"><p class="stat-title">Лабораторные</p><p class="stat-value" th:text="${labCount}">0</p>
+            <p class="hint" th:if="${labCount > 0}">опубликовано: <span th:text="${publishedLabs}">0</span></p></div>
+        <div class="card card-body"><p class="stat-title">Средний балл</p>
+            <p class="stat-value" th:if="${avgGrade != null}" th:text="${#numbers.formatDecimal(avgGrade, 1, 2)}">—</p>
+            <p class="stat-value text-muted" th:if="${avgGrade == null}">—</p></div>
     </div>
-    <div class="mt-8">
-        <div class="flex items-center justify-between mb-4">
-            <h2 class="section-title">Группы</h2>
-            <a th:href="@{/admin/groups}" class="text-sm">Все группы →</a>
+
+    <div class="grid grid-2 mt-8">
+        <div>
+            <div class="flex items-center justify-between mb-4">
+                <h2 class="section-title">Лабораторные</h2>
+                <a th:href="@{/admin/labs}" class="text-sm">Все →</a>
+            </div>
+            <div class="card card-flush">
+                <table>
+                    <tbody>
+                    <tr th:each="lab : ${labs}">
+                        <td><a th:href="@{/admin/labs/{id}(id=${lab.id})}" th:text="|ЛР ${lab.number}. ${lab.title}|">—</a></td>
+                        <td class="text-muted" th:text="${lab.variantCount} + ' вар.'">—</td>
+                    </tr>
+                    <tr th:if="${#lists.isEmpty(labs)}"><td class="empty">Лабораторных нет.</td></tr>
+                    </tbody>
+                </table>
+            </div>
         </div>
-        <div class="card card-flush">
-            <table>
-                <thead><tr><th>Название</th><th>Студентов</th></tr></thead>
-                <tbody>
-                <tr th:each="group : ${groups}"><td><a th:href="@{/admin/groups/{id}(id=${group.id})}" th:text="${group.name}">—</a></td><td th:text="${group.studentCount}">0</td></tr>
-                <tr th:if="${#lists.isEmpty(groups)}"><td colspan="2" class="empty">Групп пока нет.</td></tr>
-                </tbody>
-            </table>
+        <div>
+            <div class="flex items-center justify-between mb-4">
+                <h2 class="section-title">Группы</h2>
+                <a th:href="@{/admin/groups}" class="text-sm">Все →</a>
+            </div>
+            <div class="card card-flush">
+                <table>
+                    <tbody>
+                    <tr th:each="group : ${groups}">
+                        <td><a th:href="@{/admin/groups/{id}(id=${group.id})}" th:text="${group.name}">—</a></td>
+                        <td class="text-muted" th:text="${group.studentCount} + ' студ.'">—</td>
+                    </tr>
+                    <tr th:if="${#lists.isEmpty(groups)}"><td class="empty">Групп нет.</td></tr>
+                    </tbody>
+                </table>
+            </div>
         </div>
     </div>
 </div>