feat(homeassistant): a scheduled OS update reboots the machine and is done once the new version runs (#6755)

Home Assistant writes an OS update and leaves the reboot to someone, so a scheduled
one never finished unattended. The schedule now asks for the reboot once, follows it
through Home Assistant going away, and counts it done when the Supervisor reports a
different version with nothing pending. A machine that doesn't come back or falls
back to the old version fails after 20 minutes, which ends the slot and raises
update_failed. Install on the page and through MCP still leave the reboot to the person.

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

plugins/homeassistant/templates/homeassistant/index.html

@@ -20,7 +20,7 @@
 <div id="ha-body"{% if under_way %} hx-get="/plugins/homeassistant/" hx-select="#ha-body" hx-trigger="every 15s" hx-swap="outerHTML"{% endif %}>
 <p class="page-verdict">
   {% if under_way %}{{ status_badge('pending', 'Updating') }}
-    {{ under_way.title }}: {{ "taking a backup first" if under_way.state == 'backing_up' else "installing " ~ under_way.to_version }}. Home Assistant may stop answering for a while.
+    {{ under_way.title }}: {{ {'backing_up': "taking a backup first", 'rebooting': "rebooting into " ~ under_way.to_version}.get(under_way.state, "installing " ~ under_way.to_version) }}. Home Assistant may stop answering for a while.
   {% elif reach == 'up' %}{{ status_badge('up', 'Answering') }}
     {% if installable %}{{ installable|length }} update{{ "s" if installable|length != 1 }} waiting.{% else %}Everything Steward can update is up to date.{% endif %}
     Read {{ connection.last_polled_at|ago }}.
@@ -97,13 +97,13 @@
 <section class="card" aria-labelledby="ha-schedule">
   <h2 id="ha-schedule" class="section-title">Scheduled updates</h2>
   {% if plan and plan.enabled %}
-  <p class="field-hint">{{ plan_when }}. Next: {{ plan_next|ago }}. Add-ons first, then Core, then the OS, each after a confirmed backup. A failure ends the run and the rest wait.</p>
+  <p class="field-hint">{{ plan_when }}. Next: {{ plan_next|ago }}. Add-ons first, then Core, then the OS and its reboot, each after a confirmed backup. A failure ends the run and the rest wait.</p>
   {% else %}
   <p class="field-hint">Off. Updates are only installed when someone chooses Install.</p>
   {% endif %}
   {% if plan and plan.stopped %}<p class="tone-warn">The last run stopped early. {{ plan.stopped }}</p>{% endif %}
   {% if admin %}
-  <p class="tone-warn">A Core update restarts Home Assistant with nobody there to watch, and an update can change how automations behave. An OS update takes effect only once you reboot the machine: Steward leaves that to you, and shows it under System until it's done.</p>
+  <p class="tone-warn">A Core update restarts Home Assistant and an OS update reboots the machine, with nobody there to watch. An update can also change how automations behave.</p>
   <form method="post" action="/plugins/homeassistant/schedule" style="display:flex;flex-wrap:wrap;gap:0.75rem;align-items:flex-end;">{{ csrf_field() }}
     <label style="display:flex;gap:0.5rem;align-items:center;cursor:pointer;margin-bottom:0.4rem;">
       <input type="checkbox" name="enabled" value="on"{% if plan and plan.enabled %} checked{% endif %}> Install on a schedule
@@ -137,7 +137,7 @@
         <td class="mono">{{ r.from_version or "—" }} → {{ r.to_version or "—" }}</td>
         <td>{% if r.state == 'done' %}{{ status_badge('up', 'Done') }}
           {% elif r.state == 'failed' %}{{ status_badge('down', 'Failed') }}<div class="cell-sub">{{ r.message }}</div>
-          {% else %}{{ status_badge('pending', 'Taking a backup' if r.state == 'backing_up' else 'Installing') }}{% endif %}</td>
+          {% else %}{{ status_badge('pending', {'backing_up': 'Taking a backup', 'rebooting': 'Rebooting'}.get(r.state, 'Installing')) }}{% endif %}</td>
         <td>{{ r.started_at|ago }}</td>
       </tr>
     {% endfor %}