Rename blog.home → blog.index in not_found template

The blog index moved from / to /index; homepage now shows a Ghost page.

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

browser/templates/_types/blog/not_found.html

@@ -8,8 +8,8 @@
     The post "{{ slug }}" could not be found.
   </p>
   <a 
-    href="{{ url_for('blog.home')|host }}"
-    hx-get="{{ url_for('blog.home')|host }}"
+    href="{{ url_for('blog.index')|host }}"
+    hx-get="{{ url_for('blog.index')|host }}"
     hx-target="#main-panel"
     hx-select="{{ hx_select }}"
     hx-swap="outerHTML"