* fix(permission): handle sandbox checks without standard plan
* refactor(chat): unify helper bot with main chat flow
- route helper bot through the main chat schema and API endpoints
- align file upload, image handling, empty-output tips, and interactive payload support
- update related tests and pro submodule pointer
* chore(helperbot): clean unified chat flow leftovers
* feat: align helperbot workflow billing
* feat: optimize helper chat flow
* fix: handle helper chat resume cleanup
