Column mapping

ImportMapping defines the target module and target entity. ImportColumnMapping defines source column, staged target field, transform rule, required flag, default value, validation rules, and sort order.

Supported transform rules are deterministic: trim text, parse number, parse currency, parse date, normalize phone, normalize email, map status, map priority, map yes/no, split name, combine columns, ignore column, and custom placeholder.

Custom transforms are not executable plugins in Sprint 13. Keep custom usage as a human-readable note until a later approved sprint.