Fix fox schedule issues

[springfall2008]

No description provided.

[Copilot]

Pull request overview

This PR addresses Fox ESS scheduler write/read inconsistencies by tracking the device’s original scheduler slot count and ensuring written schedules are padded back to that same count, avoiding schedule-length mismatches.

Changes:

• Add schedule padding support (target_count) to validate_schedule() and persist the device’s scheduler group count for later writes.
• Remove the unused device_current_schedule state and switch event serial matching to use device_detail.
• Expand Fox API tests to cover schedule padding behavior and assert the tracked scheduler slot count.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
apps/predbat/fox.py	Track scheduler group count, pad validated schedules to device slot count, remove device_current_schedule, and update schedule write/test helpers.
apps/predbat/predbat.py	Bump version to v8.37.5.
apps/predbat/tests/test_fox_api.py	Update mocks for new state, add padding-focused tests, and validate device_scheduler_count.
apps/predbat/tests/test_fox_oauth.py	Remove device_current_schedule from the OAuth test mock state.