Remove unused files and dependencies

- Delete empty modules (comic/views.py, comic/urls.py, comic/forms.py), the
  empty mypy.ini, .readthedocs.yaml (no docs/ directory, pins Python 3.8) and
  setup.py (distutils is gone in Python 3.12+ and it still listed the deleted
  comic_auth; packaging is handled by pyproject.toml).
- Untrack the base64 PDF blob 'data' and the manual-only test_comics fixtures;
  the suite builds archives in tmp_path via comic/tests/factories.py. UnRAR.exe
  stays on disk for manual rarfile testing but is not in git.
- Drop unused dependencies: django-bootstrap4, django-sri, drf-extensions,
  mysqlclient, setuptools.
- build-test.ps1 no longer uses poetry.
- Ignore .venv/, .mypy_cache/, .ruff_cache/.

.gitignore

@@ -103,3 +103,13 @@ test_comics/
 test_media/
 htmlcov/
 .coverage
+
+# Virtual environment created by uv
+.venv/
+
+# Tool caches
+.mypy_cache/
+.ruff_cache/
+
+# Local-only test fixtures (kept on disk, not in git)
+data