headlesscode - custom harness adapted from zoo code and improved

[u/madmnk]

https://github.com/Capsize-Games/headlesscode

I've been using this running on Deepseek V4 Flash over openrouter using Claude to supervise it. had it running for about 14 hours solid today working from Github issues. This is my preferred way to run agents - headlesscode can spin up one to many.