feat(sdk/js): update artifacts

[cbrzn]

This PR aims to support two endpoints that were missing from the Agent Protocol Specification in the JS SDK:

• POST /agent/tasks/{task_id}/artifacts -> To upload artifacts for a given task
• GET /agent/tasks/{task_id}/artifacts/{artifact_id} -> To download artifacts from a given task
• GET /agent/tasks/{task_id}/artifacts -> Get the list of artifacts from a given task

It's worth mentioning that I've noticed that you started the migration of these SDK into their own repositories, but since it's a WIP I decided to open the PR here - If you feel that I should open the PR in the other repository just let me know (I also saw that it has some broken links).

I also have some questions regarding how the steps are handled - I noticed that in the Python SDK they're first created and the Status is defined as created but in JS we're not doing that; I updated it to be completed once the handler has finished but tbh I don't think this is handled okay, so I am looking for feedback here

Also, we're able to run a test suite in our agent with these changes. This is how I tested things :smile:

[hackgoofer]

oh amazing. @jzanecook and I will review. Thank you! oh good catch on the broken links. The python SDK is definitely more mature than the JS one. We appreciate your help. Taking a look now. :)

To your question: yes, we are planning to remove the SDKs from this repo into their respectable ones. We can do some code minor review here, but we'd love that you make Pull Requests against those other Repos instead. :)

[cbrzn]

PR migrated to https://github.com/AI-Engineers-Foundation/agent-protocol-sdk-js/pull/1