MAINT-10 review: warn when HA did not answer and TZ is UTC; test the 3 s budget

HA can take minutes to start (2026-10-05, 502 from the proxy). Then TZ holds,
which the Supervisor sets from HA's zone, so the hour stays right; only a TZ
of UTC there now logs a WARNING asking for a restart. A test pins the 3 s
budget on the zone request (a mutant without it survived).

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

goodwe_controller/app/main.py

@@ -7267,6 +7267,10 @@ async def ha_time_zone(session, token: str) -> tuple:
         return None, f"{type(err).__name__}: {text}" if text else type(err).__name__
 
 
+_UTC_NAMES = {"UTC", "ETC/UTC", "GMT", "ETC/GMT", "UCT", "ETC/UCT",
+              "UNIVERSAL", "ETC/UNIVERSAL", "ZULU", "ETC/ZULU"}
+
+
 async def maint_site_tz(session, token: str):
     """MAINT-10: the zone the maintenance start hour is read in, logged once."""
     zone, why = await ha_time_zone(session, token)
@@ -7274,6 +7278,12 @@ async def maint_site_tz(session, token: str):
     if source == "ha":
         _LOG.info("Maintenance start hour is local time in %s, from Home "
                   "Assistant.", name)
+    elif source == "tz" and name.strip().upper() in _UTC_NAMES:
+        # The Supervisor sets TZ to its copy of HA's zone, or to UTC if it has
+        # none: HA did not answer here, and UTC may not be the site's clock.
+        _LOG.warning("Maintenance start hour uses UTC, because Home Assistant "
+                     "did not answer. Restart the add-on when it is up.")
+        _LOG.debug("maintenance time zone: %s", why)
     elif source == "tz":
         _LOG.info("Maintenance start hour is local time in %s, from the "
                   "add-on's time zone. Home Assistant gave none: %s.", name, why)