Function validate_full 

pub fn validate_full(
    path: &Path,
    config: &Config,
) -> (Vec<ValidationError>, Option<String>)

Run the project’s type checker and return structured validation errors.

Returns (errors, skip_reason):

• (errors, None) — checker ran, errors may be empty (= valid code)
• ([], Some(reason)) — checker was skipped

Skip reasons: "unsupported_language", "not_found", "timeout", "error"