Merge the News page's title into the shared navy header too

Same header_extra treatment Calendar and Me just got -- a "News" title
in the app-header instead of no page heading at all.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

mobile/templates/mobile/news_list.html

@@ -6,9 +6,16 @@
     member-visible (internal or both) news item, newest first, full-width
     like Calendar's own agenda rows (see NewsListView's docstring for why
     this isn't filtered to just this account's teams the way Home's own
-    teaser is).
+    teaser is). The "News" title lives in header_extra, merged into the
+    shared navy app-header the same way Calendar's/Me's own titles are.
 {% endcomment %}
 
+{% block header_extra %}
+    <div class="mt-3">
+        <span class="font-display text-2xl font-extrabold text-white uppercase">{% trans "News" %}</span>
+    </div>
+{% endblock header_extra %}
+
 {% block content %}
     <div class="-mx-4">
         {% if page.object_list %}