Refactor Customer and User Repository Methods for ObjectID Handling

- Updated GetByIDs methods in customer and user repositories to convert string IDs to bson.ObjectID, ensuring proper handling of MongoDB object IDs.
- Enhanced error handling for ID conversion to provide clearer feedback when invalid IDs are provided.
- Modified notification service calls in customer and user services to use context.Background() for asynchronous email sending, improving concurrency management.
- Ensured consistent handling of company IDs in the customer repository for retrieving customers by companies.

internal/user/service.go

@@ -118,7 +118,7 @@ func (s *userService) Register(ctx context.Context, form *CreateUserForm) (*User
 		"role":     user.Role,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: form.Email,
 		Title:     "Welcome to Opplens",
 		Message:   fmt.Sprintf("Welcome to Opplens\nUsername: %s\nPassword: %s", strings.ToLower(form.Username), form.Password),
@@ -229,7 +229,7 @@ func (s *userService) UpdateStatus(ctx context.Context, id string, form *UpdateU
 		"status":  form.Status,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: user.Email,
 		Title:     "Account Status Updated",
 		Message:   fmt.Sprintf("Your account has been %s", strings.ToUpper(form.Status)),
@@ -495,7 +495,7 @@ func (s *userService) ChangePassword(ctx context.Context, userID string, form *C
 		"user_id": userID,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: user.Email,
 		Title:     "Password Reset Success",
 		Message:   "Your password has been reset successfully",