Function
A function that labels a runtime given in seconds
The hero's course total, a shelf's module total and a video card's own
runtime all read the same way — "8 min", "2 h", "2 h 39 min" — so the
choice between the three messages lives here once instead of in each of
them. formatDuration does the arithmetic; the message catalogue owns the
wording and word order per locale.
Works in Server Components as well as Client Components: it only calls
useTranslations.
Turns a runtime in seconds into the course overview's localized label.