Drop the sidebar's "Platform" title, add top margin

Cosmetic: the section label was redundant with the panel it lives in.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

controlpanel/templates/controlpanel/base.html

@@ -11,8 +11,7 @@
         the day the menu itself grows taller than the screen.
     {% endcomment %}
     <aside class="hidden w-64 shrink-0 overflow-y-auto border-r border-base-300 bg-base-100 lg:block">
-        <ul class="menu w-full gap-1 p-3">
-            <li class="menu-title">Platform</li>
+        <ul class="menu w-full gap-1 p-3 mt-4">
             {% include "controlpanel/_nav_items.html" %}
         </ul>
     </aside>