Fix truncated_values_count attribute error in clone_catalog

CloneCatalogResult has truncated_values (a list), not truncated_values_count.
Access the length of the list instead.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: carlkesselman

src/deriva_ml_mcp/tools/catalog.py

@@ -600,8 +600,8 @@ async def clone_catalog(
                 response["orphan_rows_nullified"] = result.report.summary.orphan_rows_nullified
                 response["fkeys_pruned"] = result.report.summary.fkeys_pruned
                 response["rows_skipped"] = result.report.summary.rows_skipped if hasattr(result.report.summary, 'rows_skipped') else 0
-                if result.truncated_values_count:
-                    response["truncated_values_count"] = result.truncated_values_count
+                if result.truncated_values:
+                    response["truncated_values_count"] = len(result.truncated_values)
                 # Include detailed report
                 response["report"] = {
                     "summary": {