Omni: Operator can traverse image-factory API paths via unsanitized `talos_version` in CreateSchematic

Omni manages Kubernetes on bare metal, virtual machines, or in a cloud. Prior to 1.6.6 and 1.7.3, managementServer.CreateSchematic in internal/backend/grpc/schematics.go passes the caller-controlled TalosVersion field to imageFactoryClient.OverlaysVersions without validating it as a version. An authenticated Operator can submit traversal segments in TalosVersion, and url.URL.JoinPath normalizes them into unintended paths on the configured image-factory host. Omni then issues HTTP GET requests to those paths and reflects error-body content, enabling same-host endpoint probing and possible disclosure of internal diagnostics while preventing redirection to another host or write requests. This issue is fixed in versions 1.6.6 and 1.7.3.