05f74f1b86
- Add UNIQUE constraint on membership_application.user_id (one app per user) - Add UNIQUE constraint on membership_fees.user_id (one fee record per user) - Add validation checks in process_application.php before inserting - Improve error messages for duplicate submission attempts - Add migration script to clean up existing duplicates before constraints - Update checkMembershipApplication to set session message on redirect - Add comprehensive documentation of duplicate prevention architecture Individual payments/EFTs are tracked separately in payments table