Hide calendar events when invitation email is marked as spam

Problem
When Gmail marks a calendar invitation as spam, Front correctly trashes the email conversation but continues to display the linked calendar event — because message sync and calendar sync run as independent pipelines. Google may hide the event in its own UI while still returning it as active via the Calendar API, leaving spam events cluttering the Front calendar after the invitation has been handled.

Request
Correlate spam or trashed invitation messages with their linked calendar events and automatically hide the associated event from the Front calendar.