refactor: extract MdrsClient service layer for library portability

To improve the tool's portability as a Python library, the core logic
has been decoupled from the CLI interface. This allows developers to
programmatically interact with MDRS without relying on CLI-specific
argument parsing or local file-based caches.

- Introduce `MdrsClient` service layer to handle core operations.
- Abstract authentication state using `CacheInterface` and `InMemoryCache`.
- Migrate all CLI commands to utilize `MdrsClient` for execution.
- Separate `Doi` data model from API responses and move to `models/doi.py`.
- Update `README.md` to include Python API usage examples.
- Bump package version to 1.3.17.

mdrsclient/commands/ls.py

@@ -55,7 +55,18 @@ class LsCommand(BaseCommand):
     @classmethod
     def ls(cls, remote_path: str, password: str | None, is_json: bool, is_recursive: bool, is_quiet: bool) -> None:
         remote = remote_path.split(":", 1)[0] if ":" in remote_path else ""
-        connection = cls._create_connection(remote)
+        from mdrsclient.client import MdrsClient
+
+        client = MdrsClient.from_remote(remote)
+        client.ls_command(remote_path, password, is_json, is_recursive, is_quiet)
+        return
+
+    @classmethod
+    def _ls_logic(
+        cls, connection, remote_path: str, password: str | None, is_json: bool, is_recursive: bool, is_quiet: bool
+    ) -> None:
+        remote = remote_path.split(":", 1)[0] if ":" in remote_path else ""
+
         folder, laboratory = cls._resolve_folder(connection, remote_path, password)
         laboratory_name = laboratory.name
         files = cls._find_files(connection, folder.id)