Creates a binary step feature: eval(i) = 1 if
values[i] > threshold, else 0.
Examples
if (FALSE) { # \dontrun{
vals <- c(1, 5, 10, 3)
f <- maxent_threshold_feature(vals, "temperature_threshold", threshold = 5)
maxent_feature_eval(f, 3) # values[2] = 10 > 5 → 1
} # }