Adds files_mcp/tools/requests.py with 9 Pydantic body models (one per tool, since fastapi-mcp passes args as JSON body) and files_mcp/tools/files.py with 9 thin wrappers that call path_guard then fs_ops and return model_dump() form. Adds tests/unit/test_files_tool.py covering happy path, sandbox escape, and KeyError/FileExistsError propagation for each wrapper. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>