parseDates was using "02.01.2006" / "01/02/2006" which require
zero-padded fields. The Czech attendance sheet headers contain dates
like "1.6.2026", "23.3.2026", "6.4.2026" — Go silently dropped those
columns while Python's strptime accepted them. Effect was a missing
2026-06 month on /api/juniors plus undercounted attendance in any month
with single-digit columns; surfaced via make parity.
Use the unpadded reference forms "2.1.2006" / "1/2/2006" instead — Go's
time.Parse accepts both padded and unpadded inputs against them.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
