Refactor Notification Management and Enhance Customer Features

- Updated the notification handling logic to utilize a new SDK for sending notifications, improving the flexibility and scalability of the notification system.
- Introduced new methods in the notification service for sending notifications to users and customers based on various target audience types, enhancing the notification delivery capabilities.
- Added a new endpoint to assign companies to a customer, improving customer management functionalities.
- Refactored the customer entity and forms to replace 'CompanyIDs' with 'Companies', ensuring consistency across the data model.
- Enhanced API documentation with Swagger comments for the new endpoint and updated notification structures, ensuring clarity for API consumers.

internal/user/repository.go

@@ -20,6 +20,7 @@ type Repository interface {
 	GetByID(ctx context.Context, id string) (*User, error)
 	GetByEmail(ctx context.Context, email string) (*User, error)
 	GetByUsername(ctx context.Context, username string) (*User, error)
+	GetByIDs(ctx context.Context, userIDs []string) ([]User, error)
 	Search(ctx context.Context, form *SearchUsersForm, pagination *response.Pagination) ([]User, int64, error)
 }
 
@@ -215,6 +216,16 @@ func (r *userRepository) Delete(ctx context.Context, id string) error {
 	return nil
 }
 
+// GetByIDs retrieves users by IDs
+func (r *userRepository) GetByIDs(ctx context.Context, userIDs []string) ([]User, error) {
+	users, err := r.ormRepo.FindAll(ctx, bson.M{"_id": bson.M{"$in": userIDs}}, orm.NewPaginationBuilder().Limit(len(userIDs)).Build())
+	if err != nil {
+		return nil, err
+	}
+
+	return users.Items, nil
+}
+
 // List retrieves users with pagination
 func (r *userRepository) Search(ctx context.Context, form *SearchUsersForm, pagination *response.Pagination) ([]User, int64, error) {
 	filter := bson.M{}