fix: use plain links for cross-app calendar navigation

HTMX blocks cross-origin hx-get requests, causing
htmx:invalidPath. Calendar links to events service must
be regular <a> tags without hx-get.

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

suma_browser/templates/_types/post/admin/_nav.html

@@ -1,7 +1,9 @@
 {% import 'macros/links.html' as links %}
-{% call links.link(events_url('/calendars/'), hx_select_search, select_colours, True, aclass=styles.nav_button) %}
-  calendars
-{% endcall %}
+<div class="relative nav-group">
+  <a href="{{ events_url('/calendars/') }}" class="{{styles.nav_button}}">
+    calendars
+  </a>
+</div>
 {% call links.link(url_for('blog.post.admin.entries', slug=post.slug), hx_select_search, select_colours, True, aclass=styles.nav_button) %}
   entries
 {% endcall %}

suma_browser/templates/_types/post/admin/_nav_entries.html

@@ -32,11 +32,6 @@
           {% set local_href=events_url('/calendars/' + calendar.slug + '/') %}
           <a
             href="{{ local_href }}"
-            hx-get="{{ local_href }}"
-            hx-target="#main-panel"
-            hx-select="{{ hx_select_search }}"
-            hx-swap="outerHTML"
-            hx-push-url="true"
             class="{{styles.nav_button_less_pad}}">
             <i class="fa fa-calendar" aria-hidden="true"></i>
             <div>{{calendar.name}}</div>