WaveLog v1 truncated every grid to four characters with gridsquare.take(4),
while v2 sent the same grid at full precision. QRZ backfill provides six-character
locators (e.g. OM89ab / FN31pr), so the v1 path - the one used by the user's
server in practice - degraded position precision from roughly 4.6 km to around
100 km and stored different data depending on which API version answered.
Send the complete grid through v1 as well. The ADIF length field is already
computed from the actual value, so six/eight-character locators need no special
handling.
TDD proof:
old take(4): v1_adif_preservesSixCharacterGrid FAILED
fixed: WaveLogApiPayloadTest BUILD SUCCESSFUL
full suite: :core:domain:test BUILD SUCCESSFUL