赵月辉 / fastgpt-migrated

* 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