Can anyone tell me why these hot & neutral wires would be connected? Their mates are connected to a breaker (black wire) and neutral bus (white wire).
Thanks in advance.
That is simply a white wire, NOT a neutral.
That is a switch loop wired into the panel. One cable is the load and the other is the switch loop.
Seeing the type of wire used (TW nm cable) it is long before the old “re-mark the white” rule took effect.
Probably for the boiler.