feat: show markets in post nav bar and admin panel

- Post context processor loads MarketPlace rows for the page
- Nav bar displays market links (shopping-bag icon) alongside calendars
- Admin panel includes markets CRUD when market feature is enabled
- Updated shared_lib submodule with nav_entries template change

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

templates/_types/post/_nav.html

@@ -1,6 +1,6 @@
 {% import 'macros/links.html' as links %}
     {# Associated Entries and Calendars - vertical on mobile, horizontal with arrows on desktop #}
-    {% if (associated_entries and associated_entries.entries) or calendars %}
+    {% if (associated_entries and associated_entries.entries) or calendars or markets %}
       <div class="flex flex-col sm:flex-row sm:items-center gap-2 border-r border-stone-200 mr-2 sm:max-w-2xl"
            id="entries-calendars-nav-wrapper">
         {% include '_types/post/admin/_nav_entries.html' %}

templates/_types/post/admin/_main_panel.html

@@ -4,8 +4,12 @@
   class="flex-1 md:h-full md:min-h-0 overflow-y-auto overscroll-contain js-grid-viewport"
 >
   {% if post and post.is_page %}
-    <div class="max-w-lg mx-auto mt-6 px-4">
+    <div class="max-w-lg mx-auto mt-6 px-4 space-y-6">
       {% include "_types/post/admin/_features_panel.html" %}
+
+      {% if features.get('market') %}
+        {% include "_types/post/admin/_markets_panel.html" %}
+      {% endif %}
     </div>
   {% endif %}
   <div class="pb-8"></div>