fix(ui): hide scroll loading indicator when no more content to load

app/templates/showcase.html

@@ -86,8 +86,10 @@
     {% endif %}
     {% endfor %}
 {% endif %}
+{% if sent_visible|length > 19 %}
 <div id="scroll-sentinel-sent" style="height:1px"></div>
 <div id="scroll-loading-sent" style="text-align:center;padding:1rem;color:var(--text-muted);display:none">⏳</div>
+{% endif %}
 </div>
 
 <div id="tab-received" class="tab-panel" style="display:none">
@@ -135,8 +137,10 @@
     {% endif %}
     {% endfor %}
 {% endif %}
+{% if received_visible|length > 19 %}
 <div id="scroll-sentinel-received" style="height:1px"></div>
 <div id="scroll-loading-received" style="text-align:center;padding:1rem;color:var(--text-muted);display:none">⏳</div>
+{% endif %}
 </div>
 {% endif %}