Update project configuration and dependencies

- Added `.vscode` to `.gitignore` to exclude Visual Studio Code settings.
- Updated `pyproject.toml` to include `ruff` for linting and configured its settings.
- Modified `uv.lock` to include `ruff` in both optional and development dependencies.
- Refactored type hints in several files to use `str | None` for optional parameters.
- Cleaned up unused imports and whitespace in various modules for improved code clarity.

oxi/conf.py

@@ -1,6 +1,7 @@
-from functools import cached_property
 import json
-from typing import TYPE_CHECKING, Generic, Iterator, TypeVar
+from collections.abc import Iterator
+from functools import cached_property
+from typing import TYPE_CHECKING, Generic, TypeVar
 
 from pydantic import BaseModel