Decouple UserType, add Role entity and management

Removed all UserType logic and references, replacing them with a new Role model and management system. Introduced RoleManager service, repository, and API endpoint for role CRUD operations. Updated user flows and JWT claims to use RoleCode. Removed admin-only user CRUD endpoints. Updated DI, documentation, and error handling for consistency. Appsettings and DTOs now reflect the new role-based approach.

Interfaces/IRoleManageRepository.cs

@@ -0,0 +1,13 @@
+using AuthHex.Models;
+
+namespace AuthHex.Interfaces
+{
+    public interface IRoleManageRepository
+    {
+        Task<Role> AddRoleAsync(Role role, CancellationToken ct = default);
+        Task<Role?> GetRoleByIdAsync(Guid roleId, CancellationToken ct = default);
+        Task<List<Role>> ListRolesAsync(CancellationToken ct = default);
+        //Task<bool> RoleInUseAsync(Guid roleId, CancellationToken ct = default);
+        Task DeleteRoleAsync(Role role, CancellationToken ct = default);
+    }
+}