Repeater and room-server administration

[singular0]

CMD_SEND_LOGIN (26), CMD_SEND_STATUS_REQ (27) and the PUSH_LOGIN_SUCCESS /
PUSH_LOGIN_FAIL / PUSH_STATUS_RESPONSE pushes are unhandled, so infrastructure nodes cannot be
administered from Corelet.

Large, and only relevant to users who run repeaters or room servers. coreletd does not implement
these either.

Tasks:

• Log in to a repeater and hold the session.
• Request and display status.
• Decide whether credentials are stored, and if so where — the app deliberately keeps secrets on
  the device today.