* fix(setup-agent): prevent data loss when setup fails on existing agent directory
Record whether the agent directory pre-existed before mkdir, and only
run shutil.rmtree cleanup when the directory was newly created during
this call. Previously, any failure would delete the entire directory
including pre-existing SOUL.md and config.yaml.
* fix: address PR review — init variables before try, remove unused result
* style: fix ruff I001 import block formatting in test file
* style: add missing blank lines between top-level definitions in test file
