fix: pagination scrambling and scroll + feat: excludePostTypes filter

- Fix duplicate x-for keys causing scrambled pagination numbers on
  interactions page (two '…' entries shared the same key)
- Fix scroll target in goToPage — was using dead closest('[x-show]')
  selector, now scrolls to #webmentions-list
- Add flex-wrap to pagination-links for mobile overflow
- Add excludePostTypes Eleventy filter to exclude post types from
  collections by detecting type from frontmatter properties
- Wire excludePostTypes into recent-posts section via sectionConfig
- Add error/stale data banner to changelog page

_includes/components/sections/recent-posts.njk

@@ -7,15 +7,17 @@
 {% set sectionConfig = section.config or {} %}
 {% set maxItems = sectionConfig.maxItems or 5 %}
 {% set showSummary = sectionConfig.showSummary if sectionConfig.showSummary is defined else true %}
+{% set excludeTypes = sectionConfig.excludeTypes or [] %}
+{% set recentPosts = collections.posts | excludePostTypes(excludeTypes) | head(maxItems) %}
 
-{% if collections.posts and collections.posts.length %}
+{% if recentPosts and recentPosts.length %}
 <section class="mb-8 sm:mb-12">
   <h2 class="text-xl sm:text-2xl font-bold text-surface-900 dark:text-surface-100 mb-4 sm:mb-6">
     {{ sectionConfig.title or "Recent Posts" }}
   </h2>
 
   <div class="space-y-4">
-    {% for post in collections.posts | head(maxItems) %}
+    {% for post in recentPosts %}
       {# Detect post type from frontmatter properties #}
       {% set likedUrl = post.data.likeOf or post.data.like_of %}
       {% set bookmarkedUrl = post.data.bookmarkOf or post.data.bookmark_of %}