Add Tender Approval Management Functionality and API Enhancements

- Introduced a new tender approval management system, including the creation of tender approval entities, services, and repositories.
- Implemented CRUD operations for tender approvals, allowing companies to approve or reject tenders.
- Developed administrative and public API endpoints for listing, retrieving, and updating tender approvals with comprehensive filtering options.
- Enhanced Swagger documentation to accurately reflect the new endpoints, including detailed descriptions, parameters, and response formats.
- Updated existing routes to include tender approval management, ensuring adherence to Clean Architecture principles and maintaining a clear separation of concerns in the handler layer.

internal/tender_approval/errors.go

@@ -0,0 +1,17 @@
+package tender_approval
+
+import "errors"
+
+// Common error messages for tender approval operations
+var (
+	ErrTenderApprovalNotFound = errors.New("tender approval not found")
+	ErrTenderApprovalExists   = errors.New("tender approval already exists for this tender and company")
+	ErrInvalidStatus          = errors.New("invalid tender approval status")
+	ErrInvalidSubmissionMode  = errors.New("invalid submission mode")
+	ErrTenderNotFound         = errors.New("tender not found")
+	ErrCompanyNotFound        = errors.New("company not found")
+	ErrInvalidTenderID        = errors.New("invalid tender ID")
+	ErrInvalidCompanyID       = errors.New("invalid company ID")
+	ErrUnauthorized           = errors.New("unauthorized to perform this action")
+	ErrInvalidData            = errors.New("invalid tender approval data")
+)