Function is_declaration_file_path 

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

True when the path’s final component looks like a TypeScript declaration file (.d.ts, .d.mts, .d.cts). Used to seed declaration files as overall entry points so ambient typeof import() references stay alive.

Keep in sync with the analysis-layer declaration-file predicate. The graph crate cannot depend on the detector backend, so the predicate is duplicated.