Replace static base currency badge with a currency dropdown (makeCDD).
Changing the selection updates state.baseCurrency, re-renders all item/line
blocks so closures capture the new base, and recalculates totals. All
dynamic references to CFG['currency-base'] replaced with state.baseCurrency.
https://claude.ai/code/session_014uUwDBtG5y5FuWcy5zqVD1
- item-name: change flex:1 to width:100% since it's not in a flex container
- FX rate: add grow class to fgrp and set input width to 100% so it extends to the right edge
https://claude.ai/code/session_014uUwDBtG5y5FuWcy5zqVD1