P2P receive over RF

As a Radiomail user, I want my iPhone to act as a P2P receiving station so two iPhones can exchange Winlink messages directly over RF without a gateway.

Acceptance: add a “P2P receive” mode that listens on a selected mode, decodes and ACKs incoming P2P sessions, stores messages locally, and logs session metadata.

Might be a battery problem keeping the phone on all the time. Perhaps this mode could be restricted to only when phone is charging.