feat: restrict user answer compaction to admin users and update related tests

generic/templates/generic/answer_history.html

@@ -66,6 +66,7 @@
                         </table>
                     </div>
                     
+                    {% if request.user.is_superuser or request.user.is_staff %}
                     <!-- Compacting tools panel -->
                     <div class="card mt-4 border-warning">
                         <div class="card-header bg-warning-subtle text-warning-emphasis fw-bold">
@@ -76,14 +77,6 @@
                                 Compacting history deletes all older versions and their associated revision logs, retaining only the final answer database state. This is permanent and cannot be undone.
                             </p>
                             <div class="d-flex flex-wrap gap-3">
-                                <form method="post" style="display:inline;">
-                                    {% csrf_token %}
-                                    <input type="hidden" name="action" value="compact_single">
-                                    <button type="submit" class="btn btn-warning btn-sm" onclick="return confirm('Are you sure you want to delete all historical edits for this individual answer?');">
-                                        Compact Single Answer
-                                    </button>
-                                </form>
-                                
                                 {% if exam or collection %}
                                 <form method="post" style="display:inline;">
                                     {% csrf_token %}
@@ -96,6 +89,7 @@
                             </div>
                         </div>
                     </div>
+                    {% endif %}
                     
                     <div class="d-flex justify-content-between mt-4">
                         <button type="button" class="btn btn-secondary" onclick="window.history.back();">Back</button>