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/migrations/versions/homeassistant_004_reboot.py

@@ -0,0 +1,34 @@
+"""Home Assistant: an update the schedule installs can reboot the machine and follow it
+
+Revision ID: homeassistant_004_reboot
+Revises: homeassistant_003_health
+Create Date: 2026-11-02
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "homeassistant_004_reboot"
+down_revision: Union[str, None] = "homeassistant_003_health"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def _under_way(states: str) -> None:
+    op.execute("DROP INDEX uq_homeassistant_update_under_way")
+    op.execute("CREATE UNIQUE INDEX uq_homeassistant_update_under_way ON homeassistant_updates ((true)) "
+               f"WHERE state IN ({states})")
+
+
+def upgrade() -> None:
+    op.add_column("homeassistant_updates",
+                  sa.Column("reboot_after", sa.Boolean, nullable=False, server_default=sa.false()))
+    op.add_column("homeassistant_updates", sa.Column("reboot_sent_at", sa.DateTime(timezone=True), nullable=True))
+    _under_way("'backing_up', 'installing', 'rebooting'")
+
+
+def downgrade() -> None:
+    _under_way("'backing_up', 'installing'")
+    op.drop_column("homeassistant_updates", "reboot_sent_at")
+    op.drop_column("homeassistant_updates", "reboot_after")