Add support for the Atomic Harness (Verifiable Coding Agent Runtime)

[mbeckenbach]

Atomic is a fork of Pi that provides a whole agent runtime with insanely wide functionality and all open source. It's really great when working on large codebases or complex workflows which run over multiple days and require to verify in reproducible ways. But it's UX is... lets say it has the typical TUI UX. :-)

It would be great if t3code could support it.

https://bastani.ai
https://github.com/bastani-inc/atomic