feat: move mandown.save_metadata into public namespace

mandown/__init__.py

@@ -8,6 +8,7 @@
     process,
     process_progress,
     query,
+    save_metadata,
 )
 from .base import BaseChapter, BaseMetadata
 from .comic import BaseComic

tests/test_io_api.py

@@ -0,0 +1,23 @@
+from pathlib import Path
+
+import mandown
+from mandown import BaseChapter, BaseComic, BaseMetadata
+
+
+def test_load_save(tmp_path: Path) -> None:
+    comic = BaseComic(
+        BaseMetadata(
+            title="Test Comic",
+            authors=["Test Author"],
+            url="",
+            genres=["Test", "Genres"],
+            description="Test Description",
+            cover_art="https://example.com/cover.jpg",
+        ),
+        [
+            BaseChapter("Test Chapter", "https://example.com/chapter"),
+        ],
+    )
+    mandown.save_metadata(comic, tmp_path)
+    loaded = mandown.load(tmp_path)
+    assert comic.asdict() == loaded.asdict()