## Issue
312 Save notification on back navigation, enable filter on mobile
## Changes
- Don't clear then filter when mounted and there are unread notifications.
- We previously clear the filter because the user could be clicking the notification bell (which is showing some number) and we ended up with a blank page because of the filter.
- Allow the filter in mobile.
- Previously, it was intentionally removed for mobile (see bd42418f). I believe it was just because we don't have the style set up for mobile. Here's my quick attempt.
4a2305dca1