fix: remove duplicate page headings across all AP templates

document.njk already renders title as h1 via the heading macro.
All 14 AP templates were also calling heading() with level 1 inside
their content block, producing two h1 elements per page. Removed
the redundant calls and moved dynamic count prefixes into the title
variable in followers/following controllers.

views/activitypub-post-detail.njk

@@ -3,8 +3,6 @@
 {% from "heading/macro.njk" import heading with context %}
 
 {% block readercontent %}
-  {{ heading({ text: title, level: 1 }) }}
-
   <div class="ap-post-detail" data-mount-path="{{ mountPath }}">
     {# Back button #}
     <div class="ap-post-detail__back">