Refactored IRepository<T> and ICatalogRepository to reside in the DbFirst.Application layer instead of Domain. Updated namespaces, using statements, and all references in services and handlers. Adjusted csproj dependencies to reflect the new structure. Updated comments to clarify Clean Architecture rationale and improved separation of concerns.
Removed unused and redundant using/import statements from multiple files, including command, repository, and Program.cs. No functional changes; this commit improves code clarity and organization.
Replaced direct service usage in CatalogsController with MediatR-based commands and queries for all CRUD operations. Added command/query and handler classes for Catalog operations. Updated dependency injection to register MediatR and removed ICatalogService. Improved code maintainability and testability by adopting CQRS architecture.
