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/config.py

@@ -38,13 +38,17 @@ class ConfigCommand(BaseCommand):
     def func_create(cls, args: Namespace) -> None:
         remote = str(args.remote)
         url = str(args.url)
-        cls.create(remote, url)
+        from mdrsclient.client import MdrsClient
+
+        MdrsClient(None).config_create(remote, url)
 
     @classmethod
     def func_update(cls, args: Namespace) -> None:
         remote = str(args.remote)
         url = str(args.url)
-        cls.update(remote, url)
+        from mdrsclient.client import MdrsClient
+
+        MdrsClient(None).config_update(remote, url)
 
     @classmethod
     def func_list(cls, args: Namespace) -> None:
@@ -53,7 +57,9 @@ class ConfigCommand(BaseCommand):
     @classmethod
     def func_delete(cls, args: Namespace) -> None:
         remote = str(args.remote)
-        cls.delete(remote)
+        from mdrsclient.client import MdrsClient
+
+        MdrsClient(None).config_delete(remote)
 
     @classmethod
     def create(cls, remote: str, url: str) -> None:
@@ -75,8 +81,10 @@ class ConfigCommand(BaseCommand):
 
     @classmethod
     def list(cls) -> None:
-        config = ConfigFile("")
-        for remote, url in config.list():
+        from mdrsclient.client import MdrsClient
+
+        client = MdrsClient(None)
+        for remote, url in client.config_list():
             print(f"{remote}:\t{url}")
 
     @classmethod