feat(pos): add POS controller and service for order creation and stock retrieval
refactor(pos): enhance stock and product category retrieval with pagination and mapping
- Created initial database schema with tables for Users, Roles, Products, and related entities.
- Added foreign key constraints to maintain data integrity across tables.
- Implemented triggers for managing stock movements on insert, update, and delete operations.
- Developed scripts to dump existing triggers and pull trigger definitions from the database.