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/mcp_tools.py

@@ -105,9 +105,9 @@ async def set_home_assistant_schedule(enabled: bool, weekday: int = 5, at_time:
 
     At each slot Steward installs add-ons, then Core, then the OS, one at a time,
     each after a confirmed backup, stopping at the first failure. A Core update
-    restarts Home Assistant with nobody watching. An OS update takes effect after
-    a reboot, which Steward leaves to a person, and `system.problems` shows it until
-    then. The first slot is the next one from now. Admin only, and audited.
+    restarts Home Assistant and an OS update reboots the machine, which Steward
+    does itself here, with nobody watching. The first slot is the next one from
+    now. Admin only, and audited.
     """
     try:
         weekly.parse_at(at_time)