letter outgoint attachment

internal/contract/letter_outgoing_contract.go

@@ -43,6 +43,7 @@ type CreateOutgoingLetterAttachment struct {
 	FileURL  string `json:"file_url" validate:"required"`
 	FileName string `json:"file_name" validate:"required"`
 	FileType string `json:"file_type" validate:"required"`
+	IsFinal  bool   `json:"is_final" validate:"omitempty"`
 }
 
 type CreateOutgoingLetterRequest struct {
@@ -79,6 +80,7 @@ type OutgoingLetterAttachmentResponse struct {
 	FileName   string    `json:"file_name"`
 	FileType   string    `json:"file_type"`
 	UploadedAt time.Time `json:"uploaded_at"`
+	IsFinal    bool      `json:"is_final"`
 }
 
 type OutgoingLetterApprovalResponse struct {