How to test: pick a range, press Start reciting, allow the microphone,
and recite aloud from the first word. Words turn white as it hears them and
red with a beep when it thinks you got one wrong or skipped it.
Recite at a normal murattal pace. It runs on a small CPU server, so the highlight
lags a second or two behind your voice — watch whether it stays in the right place,
not whether it is instant.