The settings card had a "Compute passcode" button that derived the value from the
callsign and filled the field in. It was added by request, so it stayed while the
previous commit removed the same derivation from the connection path - which left
the app contradicting itself: the background no longer invented a passcode, but the
UI still offered to.
APRS-IS treats the passcode as a licence check and states that supplying it to a
user is the software author's responsibility. APRSdroid carries the identical
algorithm in the same source file and deliberately does not use it for this, opting
to validate what the operator typed and link out to request one. Filling the field
in claims a check that nobody performed.
The button now opens the passcode request page. AprsPacket.passcode stays in
core:domain because validating an entry means recomputing the expected value, and
its import is dropped from the card, which no longer needs it.