Add Role Assignment Feature for Customers

- Introduced a new role assignment feature for customers, allowing roles to be assigned as either 'admin' or 'analyst'.
- Updated the Customer entity to include a Role field, enhancing the data model to support role management.
- Created new request and response forms for role assignment, ensuring proper validation and structured responses.
- Implemented the AssignRole method in the customer service layer, handling role assignment logic and error management.
- Added a new AssignRole handler to process role assignment requests via the API, complete with Swagger documentation for clarity.
- Updated routes to include the new role assignment endpoint, improving the administrative capabilities of the system.
- Enhanced logging for role assignment operations to ensure traceability and debugging ease.

internal/customer/entity.go

@@ -24,6 +24,14 @@ const (
 	CustomerTypeGovernment CustomerType = "government"
 )
 
+// CustomerRole represents the role of customer
+type CustomerRole string
+
+const (
+	CustomerRoleAdmin   CustomerRole = "admin"
+	CustomerRoleAnalyst CustomerRole = "analyst"
+)
+
 // Customer represents a customer in the tender management system
 // A customer can have an associated company for login purposes
 type Customer struct {
@@ -34,6 +42,7 @@ type Customer struct {
 	Password    string         `bson:"password"`
 	Status      CustomerStatus `bson:"status"`
 	Type        CustomerType   `bson:"type"`
+	Role        CustomerRole   `bson:"role"`
 	Phone       *string        `bson:"phone"`
 	CompanyIDs  []string       `bson:"company_ids"`
 	LastLoginAt *int64         `bson:"last_login_at"`