Add user avatar and profile feature, consolidate Auth and UserManagement features (#257)

web/backend/Features/Features.Users/Queries/GetUserById/GetUserByIdHandler.cs

@@ -0,0 +1,22 @@
+using Domain.Entities;
+using Domain.Exceptions;
+using Features.Auth.Repository;
+using MediatR;
+
+namespace Features.Auth.Queries.GetUserById;
+
+public class GetUserByIdHandler(IUserListRepository repository)
+    : IRequestHandler<GetUserByIdQuery, UserAccount>
+{
+    /// <exception cref="NotFoundException">Thrown when no user account exists with the given ID.</exception>
+    public async Task<UserAccount> Handle(
+        GetUserByIdQuery request,
+        CancellationToken cancellationToken
+    )
+    {
+        UserAccount? user = await repository.GetByIdAsync(request.UserAccountId);
+        if (user is null)
+            throw new NotFoundException($"User with ID {request.UserAccountId} not found");
+        return user;
+    }
+}