If displaying cents in sidebar, also display when zero cents for consistency

Nitpicky - but it would be nice if zero-cents accounts had `.00` if the option to display cents in sidebar is enabled, for visual consistency

e.g. instead of
<img width="90" alt="image" src="https://github.com/buckets/application/assets/41310948/da21cb06-f6d3-4568-b73e-3ab50854c0d9">

this
```
6,569.00
3.890.92
```