feat(doi): add DOI-based path access for commands

Support accessing repositories using DOI strings with optional subpaths
across ls, download, metadata, and file-metadata commands.

- Implement GET v3/doi/{id}/ API model and client calls
- Parse and resolve DOI paths into respective folder and files
- Extract common folder and file resolution logic to shared helpers
- Update README with example DOI-based shell commands

mdrsclient/commands/metadata.py

@@ -22,10 +22,9 @@ class MetadataCommand(BaseCommand):
 
     @classmethod
     def metadata(cls, remote_path: str, password: str | None) -> None:
-        (remote, laboratory_name, r_path) = cls._parse_remote_host_with_path(remote_path)
+        remote = remote_path.split(":", 1)[0] if ":" in remote_path else ""
         connection = cls._create_connection(remote)
-        laboratory = cls._find_laboratory(connection, laboratory_name)
-        folder = cls._find_folder(connection, laboratory, r_path, password)
+        folder, laboratory = cls._resolve_folder(connection, remote_path, password)
         folder_api = FoldersApi(connection)
         metadata = folder_api.metadata(folder.id)
         print(json.dumps(metadata, ensure_ascii=False))