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/utils/platform_helper.py

@@ -5,12 +5,12 @@ This module provides helpers for detecting the current platform and
 getting appropriate paths for KiCAD, configuration, logs, etc.
 """
 
+import logging
 import os
 import platform
 import sys
 from pathlib import Path
 from typing import List, Optional
-import logging
 
 logger = logging.getLogger(__name__)