feat: add markets and payments nav buttons, remove features panel

- Add cross-app nav buttons for markets and payments (events app)
- Remove page features panel and markets panel from blog admin
  (calendars, markets, and payments are now managed in the events app)

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

templates/_types/post/admin/_main_panel.html

@@ -3,14 +3,5 @@
   id="main-panel"
   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 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>
 </section>

templates/_types/post/admin/_nav.html

@@ -4,6 +4,16 @@
     calendars
   </a>
 </div>
+<div class="relative nav-group">
+  <a href="{{ events_url('/' + post.slug + '/markets/') }}" class="{{styles.nav_button}}">
+    markets
+  </a>
+</div>
+<div class="relative nav-group">
+  <a href="{{ events_url('/' + post.slug + '/payments/') }}" class="{{styles.nav_button}}">
+    payments
+  </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 %}