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.

AppDBContext.cs

@@ -8,8 +8,8 @@ namespace AuthHex
     {
         public AppDBContext(DbContextOptions<AppDBContext> options) : base(options) { }
         public DbSet<Models.User> Users => Set<Models.User>();
-        public DbSet<Models.UserType> UserType => Set<Models.UserType>();
-        public DbSet<Models.UserSession> UserSessions => Set<Models.UserSession>();
+        public DbSet<Models.Role> Roles => Set<Models.Role>();
+public DbSet<Models.UserSession> UserSessions => Set<Models.UserSession>();
 
         public DbSet<Models.Token> Token => Set<Models.Token>();
 
@@ -68,19 +68,13 @@ namespace AuthHex
                 .HasForeignKey(up => up.UserId)
                 .OnDelete(DeleteBehavior.Cascade);
 
-            // Configure UserType primary key
-            modelBuilder.Entity<Models.UserType>()
-                .HasKey(ut => ut.UserTypeId);
+            // Configure Role primary key
+            modelBuilder.Entity<Models.Role>()
+                .HasKey(r => r.RoleId);
 
             // Configure User primary key and relationships
             modelBuilder.Entity<Models.User>()
                 .HasKey(u => u.Id);
-
-            modelBuilder.Entity<Models.User>()
-                .HasOne(u => u.UserType)
-                .WithMany()
-                .HasForeignKey(u => u.UserTypeId)
-                .OnDelete(DeleteBehavior.Restrict);
         }
     }