feat(timeline): record a change by hand from the Timeline, a host's page or MCP log_change (#6350)

A change Steward can't see happen (a config edited, a disk swapped) is
recorded by whoever made it: what was done, its area, when (in the reader's
own zone), the hosts, what it was done to and a detail. Its author or an
admin edits or deletes it; recording, editing and deleting are audited and
those audit rows stay off the timeline. log_change records one as
"<user> via MCP", editable by the token's user.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/templates/timeline/_host_card.html

@@ -5,7 +5,10 @@
 <section class="card" aria-labelledby="host-history">
   <div style="display:flex;align-items:baseline;justify-content:space-between;gap:1rem;">
     <h3 id="host-history" class="section-title">History</h3>
-    <a class="field-hint" href="/timeline/?host={{ host.name|urlencode }}">All of {{ host.name }}'s history</a>
+    <span class="field-hint">
+      {%- if session.user_role in ('operator', 'admin') %}<a href="/timeline/changes/new?host={{ host.name|urlencode }}&amp;back={{ ('/hosts/' ~ host.id)|urlencode }}">Record a change</a> · {% endif -%}
+      <a href="/timeline/?host={{ host.name|urlencode }}">All of {{ host.name }}'s history</a>
+    </span>
   </div>
   {% if items %}
   <table class="table">
@@ -13,7 +16,7 @@
       {% for item in items %}
       <tr>
         <td class="nowrap" style="width:1%;">{{ item.entry.at|when }}</td>
-        <td>{{ entry_what(item) }}</td>
+        <td>{{ entry_what(item, '/hosts/' ~ host.id) }}</td>
         <td class="nowrap" style="width:1%;">{{ item.entry.actor }}</td>
       </tr>
       {% endfor %}