Support input_datetime controls

[springfall2008]

#4048

[Copilot]

Pull request overview

This PR addresses issue #4048 by adding explicit support for Home Assistant input_datetime helpers when Predbat writes charge/discharge window times for “OTHER” inverter setups, preventing a WebSocket reconnect/crash loop caused by calling a non-existent HA service.

Changes:

• Updated inverter option-writing logic to treat input_datetime.* entities as service-driven controls and call input_datetime/set_datetime (instead of set_value).
• Extended the test HA service stub to handle input_datetime/set_datetime.
• Added regression tests to verify charge and discharge window writes work when configured with input_datetime entities.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
apps/predbat/inverter.py	Ensures write_and_poll_option() uses input_datetime/set_datetime for input_datetime.* entities to avoid HA service_not_found errors.
apps/predbat/tests/test_infra.py	Adds a test stub handler for input_datetime/set_datetime so unit tests can validate state updates.
apps/predbat/tests/test_inverter.py	Adds regression coverage for writing charge/discharge windows via input_datetime entities (issue #4048).