Test can be run via cargo test --release.
For UI tests, they can be blessed (updated) with BLESS=1 cargo test --release.
There is currently no specific guidelines for contributing to klint. However, you should in general follow the guidelines to contribute to the Linux kernel and the Rust language.
There is no ban on using langauge models to assist development, but doing so should follow generated content guideline in the kernel. Pull requests that are fully or mainly generated by AI is not welcome and will be closed in line with burdensome PR policy of the Rust compiler.