Refactoring the backend of a custom CMS for an online store

Refactoring and modernization of the PHP backend of a custom online store engine. Optimization of legacy code has been carried out by decomposing large procedural files into functional modules by purpose. Database restructuring has been performed: normalization of the structure, implementation of pivot tables, indexing, and configuration of relations. Secure data migration from large tables to the new structure has been implemented without disrupting system operation. Overall performance optimization and code cleanup have been conducted.