Fix container nav template to render fragment HTML

Templates still used the old container_nav_widgets variable from the
widget system. Updated to render container_nav_html (fragment output)
which the context processor already provides.

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

blog/templates/_types/post/_nav.html

@@ -1,9 +1,9 @@
 {% import 'macros/links.html' as links %}
-    {# Widget-driven container nav — entries, calendars, markets #}
+    {# Container nav from fragments (calendars, markets) #}
-    {% if container_nav_widgets %}
+    {% if container_nav_html %}
       <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' %}
+        {{ container_nav_html | safe }}
       </div>
     {% endif %}
 

market/templates/_types/post/_nav.html

@@ -1,9 +1,9 @@
 {% import 'macros/links.html' as links %}
-    {# Widget-driven container nav — entries, calendars, markets #}
+    {# Container nav from fragments (calendars, markets) #}
-    {% if container_nav_widgets %}
+    {% if container_nav_html %}
       <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' %}
+        {{ container_nav_html | safe }}
       </div>
     {% endif %}