Function workspace_toplevel_v3_path 

pub fn workspace_toplevel_v3_path(install: &Path, name: &str) -> PathBuf

V3 destination path for a top-level entry under legacy workspace/.

For MemorySubentryDispatch entries the returned path is the data/<name> prefix; the caller iterates the entry’s subdir and uses memory_subentry_v3_path per subentry.