style: sort Python imports with isort

Add isort configuration (profile=black, line_length=100) to pyproject.toml,
add isort pre-commit hook, and auto-sort imports across all Python source files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

python/kicad_api/base.py

@@ -4,10 +4,10 @@ Abstract base class for KiCAD API backends
 Defines the interface that all KiCAD backends must implement.
 """
 
+import logging
 from abc import ABC, abstractmethod
 from pathlib import Path
-from typing import Optional, Dict, Any, List
-import logging
+from typing import Any, Dict, List, Optional
 
 logger = logging.getLogger(__name__)