refactor: remove events post header override (shared covers it)

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

templates/_types/post/header/_header.html

@@ -1,19 +0,0 @@
-{% import 'macros/links.html' as links %}
-{% macro header_row(oob=False) %}
-  {% call links.menu_row(id='post-row', oob=oob) %}
-    <a href="{{ coop_url('/' + post.slug + '/') }}" class="flex items-center gap-2 px-3 py-2 rounded whitespace-normal text-center break-words leading-snug">
-      {% if post.feature_image %}
-      <img
-          src="{{ post.feature_image }}"
-          class="h-8 w-8 rounded-full object-cover border border-stone-300 flex-shrink-0"
-        >
-      {% endif %}
-      <span>
-        {{ post.title | truncate(160, True, '…') }}
-      </span>
-    </a>
-    {% call links.desktop_nav() %}
-      {% include '_types/post/_nav.html' %}
-    {% endcall %}
-  {% endcall %}
-{% endmacro %}