twentyhq/ci-public ? reverse-engineered prompt

Build me the GitHub Actions workflows for this repository so it can act as a public CI runner for twentyhq/twenty preview environments.

I want the workflows to be triggered through repository dispatch, keep the logs public, and make sure no secrets are ever exposed to forks or outside triggers. Please set it up so it’s safe for public use and easy for the main Twenty repo to send dispatch events here when it needs preview CI runs.

If anything about the current GitHub Actions setup or dispatch payload needs to be checked against the latest docs, look it up online first and then wire it up cleanly.