Open source default agents `spec.yaml`

[tangrufus]

Publish spec.yaml of the default agents. So that we can learn to create custom agents and tweak minor configs, especially when kit-reference is outdated (e.g: missing oauth & v2)

[kiview]

Yes, we plan on doing this after the v2 migration, but can't currently give an ETA for this.

[phawrylak]

@kiview Which version of kit schema should be used for now? Still v1? It looks like OAuth configuration is not working correctly in v2.

[mdelapenya]

@phawrylak we are enforcing v2 from now on.

@tangrufus I'm currently working on extracting the embedded agents: kiro and copilot are already done.

Let's keep this issue open until all of them are extracted, if you mind.