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/freerouting.py

@@ -9,13 +9,13 @@ Supports two execution modes:
   - Docker: docker run eclipse-temurin:21-jre (requires Docker)
 """
 
-import os
-import subprocess
-import shutil
-import time
 import logging
+import os
+import shutil
+import subprocess
+import time
 from pathlib import Path
-from typing import Dict, Any, Optional, List
+from typing import Any, Dict, List, Optional
 
 logger = logging.getLogger("kicad_interface")