fix: properly handle 401 error in clound requirement fetch. (#14049)

Handle cloud requirements 401s with the same auth recovery flow as
normal requests, so permanent refresh failures surface the existing
user-facing auth message instead of a generic workspace-config load
error.

codex-rs/backend-client/src/lib.rs

@@ -2,6 +2,7 @@ mod client;
 pub mod types;
 
 pub use client::Client;
+pub use client::RequestError;
 pub use types::CodeTaskDetailsResponse;
 pub use types::CodeTaskDetailsResponseExt;
 pub use types::ConfigFileResponse;