a2a-client crate name

Hi

A while ago when there was no rust sdk for a2a protocol, I started working on one [here](https://github.com/agents-sh/radkit). I used the crate name `a2a-client`. Now that there is an official sdk, i can transfer this crate name to you if you would like it.

This is about transferring a crate name on crates.io. The first step is to understand the process for transferring ownership of a crate. Check the official crates.io documentation for transfer procedures. Then, coordinate with the issue author to initiate the transfer. 'Done' means the a2aproject organization owns the 'a2a-client' crate name on crates.io.

Scritto dal modello di indicizzazione a partire dal testo della issue.