**Replace Flake8 with Ruff, refactor type hints, and enhance archive processing logic**

- Removed `flake8` and `flake8-annotations` from dependencies, replaced by `ruff` for linting.
- Introduced cleaner type hinting and modern Python annotations (PEP 604 style) across multiple modules.
- Moved archive processing to a dedicated helper (`comic.archives`) for improved maintainability.
- Updated and simplified logic for archive file retrieval, directory cleaning, and user access validation.
- Improved error handling and added support for user classification restrictions in API responses.

comic/tests/test_scan_command.py

@@ -0,0 +1,31 @@
+"""Tests for the scan_comics management command."""
+
+from pathlib import Path
+
+import pytest
+from django.core.management import call_command
+
+from comic import models
+from comic.tests.factories import make_cbz
+
+
+@pytest.mark.django_db
+def test_scan_indexes_nested_directories(comic_volume: Path, reader_user) -> None:
+    nested = comic_volume / 'Series' / 'Volume 1'
+    nested.mkdir(parents=True)
+    make_cbz(nested / 'issue.cbz', pages=2)
+
+    call_command('scan_comics')
+
+    directory = models.Directory.objects.get(name='Volume 1', parent__name='Series')
+    book = models.ComicBook.objects.get(file_name='issue.cbz', directory=directory)
+    assert book.page_count == 2
+
+
+@pytest.mark.django_db
+def test_scan_without_a_user_stops_before_reading_the_volume(comic_volume: Path) -> None:
+    make_cbz(comic_volume / 'issue.cbz', pages=1)
+
+    call_command('scan_comics')
+
+    assert models.ComicBook.objects.count() == 0