- Create OTC UI form at public/otc/index.php
- Add API endpoint public/api/otc-order.php
- Extract shared DB connection to includes/db.php
- Add migration for OTC products (0006_phase1_otc_products.sql)
- Support order_source='direct' with automatic DIR- reference generation
- Include billing address capture with default values
- Add payment methods cash and paypal for direct sales
- Implement stock allocation and inventory management
