Ambient GPS drives the shared background map at street-level zoom
while idle; the idle Speed panel is gone until a ride starts; HUD
widgets are grid-snapped with auto-fit text; the Route Planner's map
render bug is fixed; routes can now be closed into a loop. All five
verified on the Android emulator, including one real bug (the first
ambient GPS fix not correcting the initial zoom) found and fixed
during that pass.