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/upload.py

@@ -49,7 +49,7 @@ class UploadCommand(BaseCommand):
 
     @classmethod
     def upload(cls, local_path: str, remote_path: str, is_recursive: bool, is_skip_if_exists: bool) -> None:
-        (remote, laboratory_name, r_path) = cls._parse_remote_host_with_path(remote_path)
+        remote, laboratory_name, r_path = cls._parse_remote_host_with_path(remote_path)
         l_path = os.path.abspath(local_path)
         if not os.path.exists(l_path):
             raise IllegalArgumentException(f"File or directory `{local_path}` not found.")