Allow JSON-compatible extra params

internal/adapter/http/handler.go

@@ -137,7 +137,7 @@ func executionTargetOverrideFromModelOverrideDTO(dto *modelOverrideRequestDTO) *
 		ServiceTier:     dto.ServiceTier,
 		ReasoningEffort: dto.ReasoningEffort,
 		APIKeyEnv:       dto.APIKeyEnv,
-		ExtraParams:     stringMapToAnyMap(dto.ExtraParams),
+		ExtraParams:     dto.ExtraParams,
 	}
 }
 
@@ -156,17 +156,6 @@ func modelParamsDTOFromExecutionTarget(target domain.ExecutionTarget) modelParam
 	}
 }
 
-func stringMapToAnyMap(src map[string]string) map[string]any {
-	if len(src) == 0 {
-		return nil
-	}
-	out := make(map[string]any, len(src))
-	for k, v := range src {
-		out[k] = v
-	}
-	return out
-}
-
 func mapValidation(v domain.ValidationResult) validationDTO {
 	return validationDTO{
 		Status:         string(v.Status),