Backend Pacients, Doctors and MedicalHistory endpoints

- added for Pacients:
POST: /register
POST: /login
POST: /reset_password
PUT: /profile
DELETE: /profile

- added for Doctors:
POST: /register
POST: /login
POST: /reset_password
PUT: /profile
DELETE: /profile

- added for MedicalHistories:
POST: /:id (only by pacient) - done
GET: /:id (only by pacient) - done
PUT: /:id (only by doctor) - done
PUT /grand_access - TODO

backend/Application/Endpoints/Doctors/Registration/DoctorRegistrationDto.cs

@@ -0,0 +1,9 @@
+namespace Application.Endpoints.Doctors.Login;
+
+public class DoctorRegistrationDto
+{
+    public string Name { get; set; }
+    public string Email { get; set; }
+    public string Password { get; set; }
+    public string Description { get; set; }
+}

backend/Application/Endpoints/Doctors/Registration/DoctorRegistrationHandler.cs

@@ -0,0 +1,49 @@
+using Application.Endpoints.Doctors.Login;
+using Application.Services.Database;
+using Core.Entities;
+
+namespace Application.Endpoints.Doctors.Registration;
+
+public class DoctorRegistrationHandler
+{
+    private readonly IDoctorRepository _doctorRepository;
+
+    public DoctorRegistrationHandler(IDoctorRepository doctorRepository)
+    {
+        _doctorRepository = doctorRepository;
+    }
+
+    public async Task<BaseResponse> Handle(DoctorRegistrationDto registrationDTO)
+    {
+        var validation = new DoctorRegistrationValidation(_doctorRepository);
+        var validationResult = await validation.ValidateAsync(registrationDTO);
+
+        if (!validationResult.IsValid)
+        {
+            var errorMessage = validationResult.Errors.Select(e => e.ErrorMessage).ToList();
+            return new BaseResponse
+            {
+                Success = false,
+                Message = string.Join(", ", errorMessage),
+                Data = null
+            };
+        }
+
+        var doctor = new Doctor
+        {
+            Email = registrationDTO.Email,
+            Password = registrationDTO.Password,
+            Name = registrationDTO.Name,
+            Description = registrationDTO.Description
+        };
+
+        await _doctorRepository.AddAsync(doctor);
+
+        return new BaseResponse
+        {
+            Success = true,
+            Message = "Doctor registered successfully",
+            Data = doctor // Be careful with sending sensitive data like Passwords
+        };
+    }
+}

backend/Application/Endpoints/Doctors/Registration/DoctorRegistrationValidation.cs

@@ -0,0 +1,37 @@
+using Application.Endpoints.Doctors.Login;
+using Application.Services.Database;
+using FluentValidation;
+
+namespace Application.Endpoints.Doctors.Registration;
+
+public class DoctorRegistrationValidation : AbstractValidator<DoctorRegistrationDto>
+{
+    private readonly IDoctorRepository _doctorRepository;
+
+    public DoctorRegistrationValidation(IDoctorRepository doctorRepository)
+    {
+        _doctorRepository = doctorRepository;
+
+        RuleFor(x => x.Email)
+            .NotEmpty().WithMessage("Email is required.")
+            .EmailAddress().WithMessage("Invalid email format.")
+            .MustAsync(BeUniqueEmail).WithMessage("Email already exists.");
+
+        RuleFor(x => x.Password)
+            .NotEmpty().WithMessage("Password is required.")
+            .MinimumLength(8).WithMessage("Password must be at least 8 characters long.");
+
+        RuleFor(x => x.Name)
+            .NotEmpty().WithMessage("Name is required.")
+            .MinimumLength(3).WithMessage("Name must be at least 3 characters long.");
+
+        RuleFor(x => x.Description)
+            .MaximumLength(3000).WithMessage("Description must not exceed 3000 characters.");
+    }
+
+    private async Task<bool> BeUniqueEmail(string email, CancellationToken cancellationToken)
+    {
+        var doctor = await _doctorRepository.FindByEmailAsync(email);
+        return doctor == null;
+    }
+}