token list: future expiry prints as "just now" at a terminal #286

At a terminal, token list prints a future expiry as "expires just now".

internal/control/token.go:112-116 renders ExpiresAt through relAge, which clamps the duration at zero (max(now.Sub(t), 0), internal/control/term.go:188) and so only handles the past. A token expiring in six days reads "expires just now". Piped output uses stamp and is correct.

• Render future times as "in 6d" (a relAge counterpart for the future, or a sign-aware relAge), and test both directions.