Allow personal inbox archive when shared inbox archive is restricted

Problem
When admins disable the archive permission to prevent accidental closure of shared inbox conversations, teammates also lose the ability to archive those conversations from their own personal inbox. This prevents users from achieving inbox zero on subscribed or followed conversations.

Request
Decouple personal inbox archiving from shared inbox archiving. Allow teammates to archive conversations from their own inbox (as a subscriber/follower) without affecting the conversation's status in the shared inbox.