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/jlcpcb_parts.py

@@ -5,13 +5,13 @@ Manages local SQLite database of JLCPCB parts for fast searching
 and component selection.
 """
 
-import os
-import sqlite3
 import json
 import logging
-from pathlib import Path
-from typing import List, Dict, Optional
+import os
+import sqlite3
 from datetime import datetime
+from pathlib import Path
+from typing import Dict, List, Optional
 
 logger = logging.getLogger("kicad_interface")