Refactor Notification Sending Logic in Customer and User Services

- Updated the notification sending logic in the customer and user service layers to send emails synchronously instead of using goroutines, improving clarity and ensuring immediate feedback on notification processing.
- Ensured that all relevant service methods (Register, UpdateStatus, RequestResetPassword, ResetPassword) are updated to reflect these changes, promoting consistency in notification handling across services.

internal/user/service.go

@@ -118,7 +118,7 @@ func (s *userService) Register(ctx context.Context, form *CreateUserForm) (*User
 		"role":     user.Role,
 	})
 
-	go s.notification.SendEmail(ctx, notification.Model{
+	s.notification.SendEmail(ctx, notification.Model{
 		Recipient: form.Email,
 		Title:     "Welcome to Opplens",
 		Message:   fmt.Sprintf("Welcome to Opplens\nUsername: %s\nPassword: %s", form.Username, form.Password),
@@ -229,7 +229,7 @@ func (s *userService) UpdateStatus(ctx context.Context, id string, form *UpdateU
 		"status":  form.Status,
 	})
 
-	go s.notification.SendEmail(ctx, notification.Model{
+	s.notification.SendEmail(ctx, notification.Model{
 		Recipient: user.Email,
 		Title:     "Account Status Updated",
 		Message:   fmt.Sprintf("Your account has been %s", strings.ToUpper(form.Status)),
@@ -488,7 +488,7 @@ func (s *userService) ChangePassword(ctx context.Context, userID string, form *C
 		"user_id": userID,
 	})
 
-	go s.notification.SendEmail(ctx, notification.Model{
+	s.notification.SendEmail(ctx, notification.Model{
 		Recipient: user.Email,
 		Title:     "Password Reset Success",
 		Message:   "Your password has been reset successfully",