feat: approval workflow with approver/backupApprover

backend/src/main/java/com/srsystem/dto/CreateTicketRequest.java

@@ -13,6 +13,8 @@ public record CreateTicketRequest(
         @NotBlank String title,
         @NotBlank String description,
         @Nullable String attachmentUrl,
-        @Nullable String attachmentName
+        @Nullable String attachmentName,
+        @Nullable Long approverId,
+        @Nullable Long backupApproverId
 ) {
 }