Catalog Item Updates Should Edit in Place, Not Create Duplicates

When prices or details change on an existing catalog item, the AI agent creates a new duplicate line item instead of updating the existing one. This breaks catalog integrity and causes downstream issues.

Catalogs are inherently dynamic. Construction material prices shift frequently. So, users need a reliable way to update catalog items over time without manual cleanup.

Expected behavior: Updating a catalog item (price, description, etc.) should modify the existing record in place, preserving its position in the hierarchy and any linked estimates or proposals.