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/commands/dynamic_symbol_loader.py

@@ -7,10 +7,10 @@ on-the-fly using TEXT MANIPULATION (not sexpdata) to preserve file formatting.
 This enables access to all ~10,000+ KiCad symbols dynamically.
 """
 
+import logging
 import os
 import re
 import uuid
-import logging
 from pathlib import Path
 from typing import Dict, List, Optional, Tuple