Merge master (0.19.1, TARIFF-24) into OPT-27 so the work has the weather hold to build on

release/1.0 (4a1f6cc) does not yet contain TARIFF-24 (PR #212, merged into
hotfix-0.19.1, then master 2932f3a). OPT-27 is about that code (the 1.5x
no-weather widening, _wx_track/weather_held), so it needs it. This is the
planned master -> release/1.0 merge's content, taken at 2932f3a; clean merge,
no conflicts.

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

goodwe_controller/DOCS.md

@@ -538,7 +538,7 @@ With battery modes on, these choices replace the *Charging and selling on price*
 
 **Cheap and expensive hours.** They come from the published day-ahead prices, as runs of consecutive 15-minute periods, not a single period.
 - The cheap run is the cheapest stretch long enough to fill the batteries that may charge, at their power.
-- An expensive hour costs at least *Battery cycle cost* (`cycle_cost_threshold_eur`, widened as for trading) more than the cheap run. The batteries hold their power until then.
+- An expensive hour costs more than the cheap run by at least *Battery cycle cost* (`cycle_cost_threshold_eur`) when a solar forecast is read, and by 1.5 times that when none is (a real-time price feed widens it further). The batteries hold their power until then.
 - The sale uses the most expensive stretch inside those hours, and never a period below 0.
 - A carried (not yet published) price is never used. A run that has started runs to its end.
 - With no prices, or too small a gap, every battery follows the house.