feat: add validation feature for row count comparison

Add a validate command that compares row counts between source and target tables after a migration.

internal/app/etl/transformers/plan.go

@@ -3,6 +3,7 @@ package transformers
 import (
 	"context"
 	"fmt"
+	"path"
 	"strings"
 	"time"
 
@@ -99,12 +100,11 @@ func computeStorageTransformationPlan(
 				}
 				b, ok := v.([]byte)
 				if !ok {
-					logrus.Warnf("to_storage: expected []byte for %s.%s.%s, got %T — passing through",
-						schema, table, sourceColName, v)
+					logrus.Warnf("to_storage: expected []byte for %s.%s.%s, got %T — passing through", schema, table, sourceColName, v)
 					return v, nil
 				}
 				// start := time.Now()
-				blobPath := fmt.Sprintf("%s/%s/%s", schema, table, uuid.New().String())
+				blobPath := path.Join(storageCol.Prefix, uuid.New().String())
 				blobURL, err := azureClient.UploadAndGetURL(ctx, blobPath, b)
 				if err != nil {
 					return nil, &custom_errors.JobError{