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/__init__.py

@@ -2,12 +2,12 @@
 KiCAD command implementations package
 """
 
-from .project import ProjectCommands
 from .board import BoardCommands
 from .component import ComponentCommands
-from .routing import RoutingCommands
 from .design_rules import DesignRuleCommands
 from .export import ExportCommands
+from .project import ProjectCommands
+from .routing import RoutingCommands
 
 __all__ = [
     "ProjectCommands",