Deleted client/credential.go and moved the Credentials struct to the api package for better modularity. Enhanced type safety in api by checking type assertions and added detailed comments in model structs.
Introduced a new method `GetTreeCategories` to provide a hierarchical structure for categories. Fixed typos in variable names and integrated utility functions for converting flat lists to nested dictionaries and vice versa. Added `TreeCategories` model for representing nested category structures.
This commit introduces new API and client modules that provide functionality for managing categories and products. It includes the creation of `.gitignore`, necessary data models, API endpoints, and client authentication using go-resty. This forms the foundation for further enhancements to the category and product management features.