deleteDraft permanently removes an unsent draft from Gmail. Use it to discard
a draft that should never be sent.
Example
automations/delete-expired-draft.automation.ts
Inputs
Every input, including
account, also accepts a compatible Signal.
The action fails if the draft was already sent or deleted, or belongs to a
different connected account.
Output
The action returns the deleteddraftId as a Signal<string>. This lets a
later action record exactly which draft was removed.