Function is_native 

pub fn is_native(path: &Path) -> bool

Whether path is a native .brink source file — an extension test only, matching brink-db’s internal file_language classification. This is the dispatch every discovery caller (brink-compiler’s prepare_driver, brink-cli’s load_git_baseline) uses to pick discover_native + RealFs/GitRev (native) over crate::Driver::discover (ink, INCLUDE BFS).