- Add database columns for last_employer_notification_at and last_employee_notification_at in cddu_contracts
- Update all email sending endpoints to record timestamps (remind-employer, relance-salarie, docuseal-signature, signature-salarie)
- Create smart reminder system with 24h cooldown to prevent spam
- Add progress tracking modal with real-time status (pending/sending/success/error)
- Display actual employer/employee email addresses in reminder modal
- Show notification timestamps in contracts grid with color coding (green/orange/red based on contract start date)
- Change employer email button URL from DocuSeal direct link to /signatures-electroniques
- Create /api/staff/organizations/emails endpoint for bulk email fetching
- Add retroactive migration script for historical email_logs data
- Update Contract TypeScript type and API responses to include new fields
