226. WiFi Signal Strength Mapper

Write a function solve that calculates WiFi coverage. Given router positions [x, y, range] and a point [px, py], return the strongest signal strength at that point (signal = max(0, range - distance)).

Example:
Input: routers = [[0,0,5]], point = [3,4]
Output: 0 (distance = 5, so 5-5 = 0)

Run this challenge interactively in Python or JavaScript when the app loads.