- Add qualification dropdown to first screen of child separation — the
  fee is a percentage of new membership value which varies by qualification
- Pass selected qualification_code to SeparationFeeCalculator (was null)
- Add /api/members/check-nid endpoint for real-time NID conflict detection
- Add client-side NID conflict check on both form_fill and create pages
- Block submission when active member has same NID (show clear error)
- Warn (orange) when potential/inactive member exists (will auto-archive)
- Server-side validation: reject if active NID conflict in store/saveFillForm
- Validate qualification_code required for child_separation in store()
- Add phone format validation on form_fill submit
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>