- weather_detail: scrollable hourly forecast (time, temp, description,
rain probability), data logic ported from old weather_detail_screen.cpp
- calendar_detail: scrollable list of all 10 events (summary + formatted
date/all_day), ported from old calendar_detail_screen.cpp
- mvg: scrollable departures list (line badge U/S colored, destination,
time/delay, cancellation), 1-minute refresh timer ported from old
mvg_screen.cpp
- all three use back_button widget (fixed bottom-left)
- main.cpp: Screen controller, navigates between screens via callbacks,
5-minute inactivity timeout -> home, per-screen tick() for refresh