openai/gpt-chat-latest → B (3:2)

Side B makes a coherent API change by removing the `agents_bound` field from the shared `WhoamiResponse` type, the server response, and the CLI output, simplifying the wire protocol and eliminating now-unneeded computation. Side A only deletes the `rust-toolchain.toml` pin to avoid toolchain conflicts, which is useful for development and CI configuration but is a narrower infrastructure change.