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/schedule.py

@@ -1,7 +1,7 @@
 # plugins/homeassistant/schedule.py
 """Installing what's waiting at a weekly slot: one at a time through the same path
 as the page's Install, each after its own confirmed backup. Add-ons go first and
-the OS last, as it waits on a reboot. The first failure ends the slot, leaving the
+the OS last, as it reboots the machine. The first failure ends the slot, leaving the
 rest for someone to look at. Everything is on the rows, so a restart of Steward or
 of Home Assistant only delays the next step."""
 from __future__ import annotations
@@ -76,7 +76,7 @@ async def step(app, transport=None) -> None:
     if update is None:
         return
     try:
-        await start_update(app, update["entity_id"], ACTOR, transport)
+        await start_update(app, update["entity_id"], ACTOR, transport, reboot_after=update["kind"] == "os")
     except CannotStart as exc:
         await _stop(app, schedule.id, f"{update['title']} wasn't started: {exc}. Nothing more was installed in this slot.")