fix(homeassistant): storage reads used of total with its percentage, and an OS update is said to wait on a reboot (#6753, #6754)

The tile shows Home Assistant's own used figure beside the total, so it matches
Home Assistant's storage page. An OS update doesn't reboot the machine: Supervisor
writes the image, reports the new version and raises a repair asking for a reboot.
The confirmation, schedule warning, MCP docs and plugin docs now say so.

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

plugins/homeassistant/updates.py

@@ -19,7 +19,9 @@ logger = logging.getLogger(__name__)
 
 UNDER_WAY = ("backing_up", "installing")
 BACKUP_DEADLINE_S = 30 * 60
-# An OS update reboots the machine, and a Pi is slow to come back.
+# An OS update downloads and writes a whole system image, which is slow on a Pi. Home
+# Assistant reports the new version as soon as that's written, before the reboot that
+# makes it run, and raises a repair asking for that reboot.
 INSTALL_DEADLINE_S = {"addon": 20 * 60, "core": 30 * 60, "os": 45 * 60}