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/_rows.html

@@ -8,7 +8,7 @@
       {% if item.opens_group %}<tr class="table-divider"><th colspan="5" scope="rowgroup">{{ item.group }}</th></tr>{% endif %}
       <tr>
         <td class="nowrap">{{ e.at|when }}</td>
-        <td>{{ entry_what(item) }}</td>
+        <td>{{ entry_what(item, back) }}</td>
         <td>{{ entry_where(e) }}</td>
         <td class="nowrap">{{ e.actor }}</td>
         <td class="nowrap"><span class="chip">{{ item.area_label }}</span></td>