chore: add Ruff and apply formatting across codebase

Introduce ruff lint/format config, expand .gitignore, and reformat Python sources.

Co-authored-by: Cursor <cursoragent@cursor.com>

imagepipeline/core/step.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Any, TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 if TYPE_CHECKING:
     from imagepipeline.modules.base import BaseModule