fix: sparkline width regression, dark mode pill contrast, interaction icons

- Sparkline: change from fixed 120/180px to fluid width (flex-1 min-w-0)
  filling the content area next to page titles across all 8 post type pages
- Blog filter: fix dark mode active pill contrast (dark:bg-accent-700)
- Interactions: replace wrong share icon with correct ActivityPub logo
- Interactions: add IndieWeb webmention provenance badge (globe icon)
- Interactions: improve platform detection (Bridgy Fed, more Fediverse instances)

Confab-Link: http://localhost:8080/sessions/0ec83454-d346-4329-8aaf-6b12139bf596

bookmarks.njk

@@ -14,7 +14,7 @@ permalink: "bookmarks/{% if pagination.pageNumber > 0 %}page/{{ pagination.pageN
     <h1 class="text-2xl sm:text-3xl font-bold text-surface-900 dark:text-surface-100">Bookmarks</h1>
     {% set sparklineSvg = collections.bookmarks | postingFrequency %}
     {% if sparklineSvg %}
-    <span class="text-amber-600 dark:text-amber-400">{{ sparklineSvg | safe }}</span>
+    <span class="flex-1 min-w-0 text-amber-600 dark:text-amber-400">{{ sparklineSvg | safe }}</span>
     {% endif %}
   </div>
   <p class="text-surface-600 dark:text-surface-400 mb-6 sm:mb-8">