Add Orbi to AI Agents & Autonomous Coding

[xqliu]

Adds Orbi to AI Agents & Autonomous Coding (one row, at the bottom of the table).

Against the quality bar:

1. Live URL: https://orbi.build/ returns 200.
2. License and docs: AGPL-3.0 license file and a README with setup at https://github.com/orbi-build/orbi.
3. Recent activity: commits and tagged releases land most days.
4. Real value: it turns a labelled GitHub Issue into a reviewed, merged change and a tagged release, with a separate review session gating every merge.
5. One entry in this PR.

Disclosure: I maintain Orbi.