831b6d3301 removed the view, and this line in
the cleanup SQL.
The DB migration for 6-char IDs fails to apply if this view exists - so even
though the view itself no longer exists in the code, we should always drop
it on cleanup.
- Allowed adding ephemeral(ish) views and functions
- Moved message_count to a concrete database field
- Moved most proxy logic to a stored procedure
- Moved database files around and refactored schema manager