fix: map integration link guard to API v2 conflicts

The v2 item and workspace delete routes replaced the internal handlers that
translated the protected-link guard into HTTP 409. Without a mapping the guard
surfaced as a 500, so both error funnels now return the same conflict response
as the v1 handlers.

Author: Optic00

internal/restapi/v2/items.go

@@ -715,6 +715,9 @@ func itemError(err error) error {
 	if errors.Is(err, services.ErrItemTypeMigrationRequired) {
 		return newError(http.StatusConflict, "migration_required", err.Error())
 	}
+	if errors.Is(err, services.ErrItemHasProtectedIntegrationLinks) {
+		return newError(http.StatusConflict, "conflict", "Remove all protected integration links from the affected items before deleting them.")
+	}
 	if errors.Is(err, services.ErrBulkItemNotFound) {
 		return newError(http.StatusNotFound, "not_found", "Item not found")
 	}

internal/restapi/v2/scoped_catalog.go

@@ -261,6 +261,8 @@ func workspaceMutationError(err error) error {
 		return newError(http.StatusBadRequest, "invalid_request", err.Error())
 	case errors.Is(err, repository.ErrDuplicateEntry):
 		return newError(http.StatusConflict, "conflict", "Workspace key already exists")
+	case errors.Is(err, services.ErrWorkspaceHasProtectedIntegrationLinks):
+		return newError(http.StatusConflict, "conflict", "Remove all protected integration links from this workspace before deleting it.")
 	case errors.Is(err, services.ErrInvalidWorkspaceTemplate), errors.Is(err, services.ErrWorkspaceTemplateTooLarge), errors.Is(err, services.ErrPersonalWorkspaceTemplate):
 		return newError(http.StatusUnprocessableEntity, "unprocessable_entity", err.Error())
 	default: