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/customer/form.go

@@ -60,6 +60,7 @@ type CustomerResponse struct {
 	CreatedAt   int64             `json:"created_at"`
 	LastLoginAt *int64            `json:"last_login_at"`
 	Companies   []*CompanySummary `json:"companies"`
+	DeviceToken []string          `json:"-"`
 }
 
 // ToResponse converts Customer to CustomerResponse