Complete distribution flow and student UI

- progress-service: Distribute variants (round-robin per lab per level),
  student level assignment, API for levels/assignments
- progress-service: Inter-service clients (academic, identity) via RestClient
- web: Admin lab detail page with distribute/level buttons
- web: Student dashboard shows assigned labs from progress-service
- web: ApiClient methods for labs detail, distribute, levels, me/assignments
- academic-service: Add id to LabLevelDetail DTO for progress-service
- Fix: CSS-only layout, footer at bottom via flex column

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

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html lang="ru" xmlns:th="http://www.thymeleaf.org" th:replace="~{fragments/base :: layout(~{::title}, ~{::#content})}">
+<head><title>Лабораторные — LMS</title></head>
+<body>
+<div id="content">
+    <h1 class="page-title">Лабораторные</h1>
+    <div th:if="${notice}" class="alert alert-success" th:text="${notice}"></div>
+    <div th:if="${error}" class="alert alert-error" th:text="${error}"></div>
+    <div class="grid grid-2">
+        <form class="card form-card form-stack" th:action="@{/admin/labs/import}" method="post" enctype="multipart/form-data">
+            <h2 class="section-title">Импорт лабораторной</h2>
+            <p class="text-sm text-muted">Принимаются .zip (lab.yaml + README.md + variants/*.md) или .json (старый формат).</p>
+            <div><label class="label" for="labFile">Файл</label><input class="input" id="labFile" name="file" type="file" accept=".zip,.json" required></div>
+            <button class="btn btn-primary" type="submit">Импортировать</button>
+        </form>
+    </div>
+    <div class="card card-flush mt-8">
+        <table>
+            <thead><tr><th>№</th><th>Название</th><th>Семестр</th><th>Вариантов</th><th>Статус</th><th></th></tr></thead>
+            <tbody>
+            <tr th:each="lab : ${labs}">
+                <td th:text="${lab.number}">1</td>
+                <td th:text="${lab.title}">—</td>
+                <td class="text-muted" th:text="${lab.semesterTitle}">—</td>
+                <td th:text="${lab.variantCount}">0</td>
+                <td><span class="badge" th:classappend="${lab.status == 'published'} ? 'badge-ok' : 'badge-warn'" th:text="${lab.status}">—</span></td>
+                <td class="text-center">
+                    <form th:action="@{/admin/labs/{id}/delete(id=${lab.id})}" method="post" onsubmit="return confirm('Удалить лабораторную ${lab.title}?')">
+                        <button class="nav-link text-sm" type="submit">Удалить</button>
+                    </form>
+                </td>
+            </tr>
+            <tr th:if="${#lists.isEmpty(labs)}"><td colspan="6" class="empty">Лабораторных пока нет.</td></tr>
+            </tbody>
+        </table>
+    </div>
+</div>
+</body>
+</html>