- All 7 models: created_at/updated_at changed from datetime to timestamp type
(DDL template auto-generates DEFAULT CURRENT_TIMESTAMP for timestamp type)
- core.py: fix all sor.U() calls passing 3 args (id must be in data dict)
- core.py: fix sor.I() misuse for INSERT (should be sor.C())
- API dspy updates: fix sor.U() 3-arg bug in category/product/type_config/resource/subscription/supplier
- product_resource_supplier_update.dspy: add missing updated_at field