fix: show settings cog on all services (use g.rights.admin)

has_access('settings.home') checks for a coop-only endpoint that doesn't
exist in market/cart/events services. Replace with g.rights.admin which
is set by the shared user_loader across all services.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

suma_browser/templates/_types/root/_nav_panel.html

@@ -1,5 +1,5 @@
   {% import 'macros/links.html' as links %}
-  {% if has_access('settings.home') %}
+  {% if g.rights.admin %}
     <a href="{{ coop_url('/settings/') }}" class="{{styles.nav_button}}">
       <i class="fa fa-cog" aria-hidden="true"></i>
     </a>