Busiest Dispatch Window

Find which fixed-length dispatch window received the most delivery requests.

A drone delivery hub logs the minute-of-day each delivery request comes in, from 0 to 1439. Requests are grouped into dispatch windows of a fixed length in minutes, starting from minute 0. For each request, find which window it falls into by dividing its time by the window length and dropping any remainder. Count how many requests fall into each window. Return the window with the most requests, as a tuple `(window_index, count)`. If two or more windows tie for the most requests, return the one with the smallest window index.