Radio and Connection Sleep/Reopen

This is an enhancement request to provide for dropping a connection and shutting off the radio after a specified time period of no use or after a fixed time period. Upon request e.g. post(), WifiManager will turn on the radio and reestablish the connection and reset the timer. This could be useful for battery-powered projects where always-on radio and connections will drain the battery quickly.

Start by reviewing the WifiManager connection lifecycle and the post() request path. Define how inactivity and fixed-duration timers should control the radio and connection, how requests reopen them, and what tests or observable behavior demonstrate that the timers reset correctly.

Written by the indexing model from the issue text.