Address backend implementation review findings

convert.go

@@ -4,6 +4,7 @@ import (
 	"reflect"
 
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+	"gitea.maximumdirect.net/eric/promptkit/internal/jsonvalue"
 )
 
 func toDomainRunRequest(req RunRequest) (domain.RunRequest, error) {
@@ -133,7 +134,7 @@ func toDomainExecutionTargetOverride(override *ExecutionTargetOverride) (*domain
 	if override == nil {
 		return nil, nil
 	}
-	extraParams, err := copyPublicJSONMap(override.ExtraParams)
+	extraParams, err := jsonvalue.CopyMap(override.ExtraParams)
 	if err != nil {
 		return nil, err
 	}