fix(ui): cached notificationsCount should only grow over time

[mattyg]

Cached notifications count should never shrink (i.e. if an authority has a smaller count than a prior queried authority, ignore it).

Improves #189

[jost-s]

The number of the badge grows over time or remains equal as expected when reopening the web app. However, it always goes down to 7 when I go to the notifications page.

Is that expected?

[mattyg]

The number of the badge grows over time or remains equal as expected when reopening the web app. However, it always goes down to 7 when I go to the notifications page.

Is that expected?

In theory the number by 1 every time a previously unseen notification comes into the viewport. Have you scroll down to the end of the list of notifications?

[jost-s]

Yeah, that makes sense.