The members table has date_of_birth as NOT NULL, but the wizard passed
null when no explicit DOB was entered. Now NationalIdParser extracts
DOB and gender from the 14-digit national ID for the main member,
spouses, children, and temporary members.

If no NID and no DOB provided, returns a clear validation error instead
of letting the DB constraint violation propagate.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>