Fixes bug where lifecycle sensor attributes (data_completeness, tomorrow_available)
didn't update after tomorrow data was successfully fetched from API.
Root cause: DataTransformer had cached transformation data but no mechanism to detect
when source API data changed (only checked config and midnight turnover).
Changes:
- coordinator/data_transformation.py: Track source_data_timestamp and invalidate cache
when timestamp changes (detects new API data arrival)
- coordinator/data_transformation.py: Integrate period calculation into DataTransformer
(calculate_periods_fn parameter) for complete single-layer caching
- coordinator/core.py: Remove duplicate transformation cache (_cached_transformed_data,
_last_transformation_config), simplify _transform_data_for_*() to direct delegation
- tests/test_tomorrow_data_refresh.py: Add 3 regression tests for cache invalidation
(new timestamp, config change behavior, cache preservation)
Impact: Lifecycle sensor attributes now update correctly when new API data arrives.
Reduced code by ~40 lines in coordinator, consolidated caching to single layer.
All 350 tests passing.
