Update Dimens class

Replace

```
class Dimens {
static const List buttonTopDimens = [28, 0, 28, 8];
static const List buttonBottomDimens = [28, 8, 28, 0];
static const List buttonDimens = [10, 0, 10, 0];
static const List none = [0, 0, 0, 0];
}
```

with enumeration (check Wallet code)

Locate the Dimens class and inspect the Wallet code for the enumeration pattern referenced in the issue. Replace the listed constants with the corresponding enumeration and verify that existing references still work and the project builds successfully.

Written by the indexing model from the issue text.