Phase 4: grade comments with frequency-ranked suggestions

- progress comment_templates (tone + use_count) and grade_comments tables;
  setGrade now accepts comments list; templates created/bumped automatically;
  GET /api/v1/comment-templates?q= returns suggestions ranked by frequency
- admin group page: per-grade ✎ dialog (score + editable comment rows with
  tone, datalist suggestions), chips under each score, data-comments JSON attr
- student lab page: score + colored tone chips
- fixed damaged button/attributes from earlier manual template surgery

web/src/main/resources/templates/student/lab.html

@@ -8,6 +8,9 @@
         <h1 class="page-title" th:text="|Лабораторная работа ${lab.number}. ${lab.title}|">ЛР</h1>
         <div class="flex gap-2 text-sm">
             <span th:if="${grade != null}" class="badge badge-ok">Оценка: <span th:text="${grade}"></span></span>
+            <span th:each="c : ${gradeComments}" class="chip"
+                  th:classappend="${c.tone == 'positive'} ? chip-pos : (${c.tone == 'negative'} ? chip-neg : chip-neu)"
+                  th:text="${c.text}">коммент</span>
             <span th:if="${assignment != null}" class="badge badge-warn">Вариант <span class="font-mono" th:text="${assignment.variantNumber}"></span></span>
         </div>
     </div>