Add experiment #67

[rh-hemartin]

• Add experiment related with issue Experiment: authenticate coding agents via GitHub App instead of user credentials #67.
• Apps can generate short lived tokens for certain repositories on their installations, so we can create tokens on demand and pass them to certain agents or use them in the wrappers themselves.
• Push can be done with x-access-token and the token: see https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/authenticating-as-a-github-app-installation

[rh-hemartin]

I had to ignore some stuff with uvx as it is scanning all the stuff on the repo, not just my files. This lead to unresolved imports and some unresolved attributes from a previous experiment. I created a followup story to reenable those at some point: #100

[ralphbean]

This is awesome. Thank you!

[waynesun09]

For the GitHub Actions case, the token-minting function here is covered by actions/create-github-app-token@v3, which handles the JWT → installation token exchange as a single workflow step. PR #119 uses this for both fullsend-agent[bot] and fullsend-reviewer[bot] identities.