Implements DayActivityData, fetchDayActivityData, computeRunStates,
clockTickerProvider, todayKeyProvider, programmerActivitySignalProvider,
programmerDayDataProvider, and programmerRunStatesProvider in
lib/providers/programmer_day_data_provider.dart.
Includes four passing tests in test/programmer_day_data_test.dart
covering run-state computation and day-scoped activity fetching.
Co-Authored-By: claude-flow <ruv@ruv.net>
redz1029