Each battery gets an MQTT-discovered Mode select and Use switch, only while
battery_modes_enabled is true. Commands go through handle_action(), the
/action path; refusals are logged once. Retained commands are never applied.
Turning modes off removes exactly the configs announced (kept in the store).
With modes off the announcement is byte-identical to ed739d4.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>