Feature: Badge count

Add automated badge counter.

There are two different ways of thinking about counters:
- Non-specific messages increments a "count" - this is reset on app open
- Trackable messages sets an id in the "counter" object - The app actively sets id as read

The badge is the sum of these two and is kept updated automatically.

We want an option to set a limit on the sum of unread messages, this could be set as one of three:
- Total unread limit - the limit of the sum of both counters
- Total unread of Non-specific
- Total unread of Trackable

If the limit is reached the server will skip messages for that user, at the same time we want a `force` option on send - but this should only be allowed on the server send api.

The issue names no files or tests, so first map the existing non-specific count, trackable counter object, badge updates, and server send API. Clarify the three limit modes and force behavior, then verify that badge totals update automatically, limited messages are skipped, and force is restricted to server sends.

Written by the indexing model from the issue text.