[2026-08-28] Improved: New option Shyftconnect::AssignmentSubstitution for shyftplan entity type in external record mappings

Endpoint:

• v1/external_record_mappings
• v1/external_record_mappings/{id}

Method: GET, POST, PUT

Change:

• New option Shyftconnect::AssignmentSubstitution to be used for parameter shyftplan_type, to filter external record mappings (GET) or create a new mapping (POST).