[RFC] How to set "run_at": "document_start"

[wangrongding]

How do you envision this feature/change to look/work like?

I can't find any instructions on how to set this property, does plasmo currently support it?

What is the purpose of this change/feature? Why?

(OPTIONAL) Example implementations

No response

(OPTIONAL) Contact Details

No response

Verify canary release

• I verified that the issue exists in plasmo canary release

Code of Conduct

• I agree to follow this project's Code of Conduct
• I checked the current issues for duplicate problems.