fix: pagination, headers, avatars, tab order, and notification UI

- Fix cursor pagination: use string comparison (not Date objects) for
  published field queries in both timeline and notifications
- Fix "Older" cursor to use oldest item's date, not newest
- Remove redundant parent breadcrumb from all AP page headings
- Reorder tabs: Notes first, All last
- Fix avatar loading: non-destructive hide/show with lazy loading
- Add actor avatars with type badge overlay to notification cards
- Add Fediverse navigation group in sidebar

views/activitypub-post-detail.njk

@@ -3,11 +3,7 @@
 {% from "heading/macro.njk" import heading with context %}
 
 {% block readercontent %}
-  {{ heading({
-    text: title,
-    level: 1,
-    parent: { text: __("activitypub.reader.title"), href: mountPath + "/admin/reader" }
-  }) }}
+  {{ heading({ text: title, level: 1 }) }}
 
   <div class="ap-post-detail" data-mount-path="{{ mountPath }}">
     {# Back button #}