style: apply Black formatting to all Python files

Add [tool.black] config to pyproject.toml and Black hook to
.pre-commit-config.yaml (rev 26.3.1), then auto-format all Python
source and test files with line-length=100, target-version=py310.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

python/commands/board.py

@@ -8,4 +8,4 @@ It imports and re-exports the BoardCommands class from the board package.
 from commands.board import BoardCommands
 
 # Re-export the BoardCommands class for backward compatibility
-__all__ = ['BoardCommands']
+__all__ = ["BoardCommands"]