Spots that include subsquare (EM12kl), extended-square (EM12kl37),
or extended-extended-subsquare (EM12kl37ab) precision now keep
that resolution end-to-end. Previously we truncated everything to
4 chars at parse time, which collapsed distinct paths into the same
row whenever two spotters shared a field.
The aggregation key uses the full grid as reported, so two
spotters in different subsquares of `EM12` produce two rows —
correct, since they are physically different paths. Any spot that
fails Maidenhead validation (odd length, illegal char at position
N) is still dropped via the same error path.
Storage normalizes to uppercase so the unique index doesn't split
on case. Maidenhead.valid?/1 already accepts both cases on input.
Graham McIntire
b924cc2fc2