Rover: Plan screen's WP radius field cannot be updated

If using Rover the Plan screen's WP Radius field can be updated but the change doesn't stick. To be more precise, the WP_RADIUS parameter isn't update and if the user moves to another screen and then back to the Plan screen the number is back to the WP_RADIUS's value. We should either make it so that the parameter cannot be updated for Rover or we should make it work.

Start by reproducing the issue in Rover on the Plan screen: edit the WP Radius field, switch screens, and return to confirm whether it reverts to WP_RADIUS. Trace the Plan screen's WP Radius handling and parameter update path. Done means the field either cannot be edited for Rover or the WP_RADIUS change persists after navigation.

Written by the indexing model from the issue text.