Function contract_lints 

pub fn contract_lints(
    h: &Htl,
    root: &Path,
    cfg: &HtlConfig,
    file: &Path,
) -> Result<Vec<String>>

contract lint for one file: when file sits directly under a [[contract]] dir of cfg (relative to root, the directory holding htl.toml), check it against that contract statically. Returns lint lines (empty when no contract applies).