IT Assets: make GDPR Mask function discoverable from users list

- Users list: add eye-slash icon button per unmasked row (editor+ only)
  clicking opens a compact confirmation modal inline in the list
- User detail: gate Edit / Assign / Mask buttons behind is_editor check
  (button was shown to all but route already blocked readonly users)

IT_asset_management/app/templates/users/detail.html

@@ -14,7 +14,7 @@
     {% if user.is_masked %}<span class="badge badge-masked fs-6 align-middle ms-2">MASKED</span>{% endif %}
   </h1>
   <div class="d-flex gap-2">
-    {% if not user.is_masked %}
+    {% if not user.is_masked and current_user.is_editor %}
     <a href="{{ url_for('users.edit', user_id=user.id) }}" class="btn btn-sm btn-outline-primary">
       <i class="bi bi-pencil me-1"></i>Edit
     </a>