Fee configuration is not saved

**Expected behavior**

Going to settings, setting fee rates for tx and collaborators, doing cj, coming back after a week, doing cj again and it uses the previously configured fees

**Actual behavior**

Configured fees are reset to their standard values again each time the user tries to do a cj

**Steps to reproduce the problem**
1. Set fees
2. Do cj
3. Come back later, do cj again -> standard fees

**Specifications**
- Version: 0.1.5
- Platform: Umbrel on Amd64
- Browser: vanadium & libre wolf

**Additional context**
Maybe this is intended to not forget about too low tx fees but its somewhat annoying, at least the collaborator fees should be persistent