Optional startup scripts and host-side prelaunch support.
- Added optional host-side
hostScriptsupport before Docker startup. - Made container-side
setupScriptoptional in the launch contract and runtime path. - Shared one timeout budget across host preparation, container preparation, and handler startup.
- Added unit coverage for host-script execution, failure handling, timeout carry-over, and missing startup scripts.
- Updated package metadata and changelog for release 0.7.0.