fix: reply readers show avatar photos instead of always showing initials

Reply seen-by section was hardcoded to show initials only.
Added avatar_path check matching topic readers pattern.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

templates/forum/topic.html

@@ -1277,8 +1277,8 @@
                     {% for read in reply.readers[:15] %}
                     <div class="reader-avatar"
                          data-name="{{ read.user.name or read.user.email.split('@')[0] }}{% if current_user.is_authenticated and read.user.id == current_user.id %} (Ty){% endif %}"
-                         style="background: hsl({{ (read.user.id * 137) % 360 }}, 65%, 50%);">
-                        {{ (read.user.name or read.user.email)[0]|upper }}
+                         style="{% if not read.user.avatar_path %}background: hsl({{ (read.user.id * 137) % 360 }}, 65%, 50%);{% endif %}">
+                        {% if read.user.avatar_path %}<img src="{{ url_for('static', filename=read.user.avatar_path) }}" alt="">{% else %}{{ (read.user.name or read.user.email)[0]|upper }}{% endif %}
                     </div>
                     {% endfor %}
                     {% if reply.readers|length > 15 %}