GHSA-qqc3-94qv-7fw3: Hubuum client library (Rust): Configured custom transports may be bypassed, exposing credentials and network traffic

When an application configures hubuum_client with ClientBuilder::with_transport, several client operations still use the built-in reqwest client directly. The bypass includes password login, bearer-token validation, authentication-provider discovery, health and readiness probes, export-output downloads, and unified-search streams.