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/DOCS.md

@@ -1653,7 +1653,8 @@ help - see "Why the tuning is what it is".
 **The start hour is local time.** The add-on reads Home Assistant's time zone
 (Settings → System → General) at startup. If Home Assistant does not answer,
 it uses the add-on's own time zone, and failing that UTC. The log says which
-one it used. On the day the clocks go forward, a start hour that does not exist
+one it used, and warns if it is UTC: then restart the add-on once Home Assistant
+is up. On the day the clocks go forward, a start hour that does not exist
 starts at the first hour after the jump. On the day they go back, a repeated
 hour starts only once, in its first pass. With two inverters both batteries use
 the same local hour; one cycles at a time, and the other starts at that hour on