Address code review feedback on Hypothesis and classic_theme changes

- Update hypothesis to latest version (>=6.151.9)
- Remove pythonpath pytest config (was only needed for tests.strategies)
- Consolidate classic_theme.py into single file with all design models
- Move Hypothesis strategies from strategies.py into their test files
- Add noqa: ARG001 to unused yaml_field_override CLI parameter
- Fix lint and type errors across the codebase

tests/cli/render_command/test_render_command.py

@@ -28,7 +28,7 @@ class TestCliCommandRender:
             "dont_generate_png": False,
             "watch": False,
             "quiet": False,
-            "_": None,
+            "yaml_field_override": None,
             "extra_data_model_override_arguments": context,
         }