feat: redesign weight summary legend and add currency selector

Redesign WeightSummaryCard stats from a disconnected 4-column grid to a
compact legend-style list with color dots, percentages, and a divider
before the total row. Switch chart and legend colors to a neutral gray
palette.

Add a currency selector to settings (USD, EUR, GBP, JPY, CAD, AUD) that
changes the displayed symbol across the app. This is visual only — no
value conversion is performed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/client/components/ItemPicker.tsx

@@ -1,4 +1,5 @@
 import { useEffect, useState } from "react";
+import { useCurrency } from "../hooks/useCurrency";
 import { useItems } from "../hooks/useItems";
 import { useSyncSetupItems } from "../hooks/useSetups";
 import { useWeightUnit } from "../hooks/useWeightUnit";
@@ -22,6 +23,7 @@ export function ItemPicker({
 	const { data: items } = useItems();
 	const syncItems = useSyncSetupItems(setupId);
 	const unit = useWeightUnit();
+	const currency = useCurrency();
 	const [selectedIds, setSelectedIds] = useState<Set<number>>(new Set());
 
 	// Reset selected IDs when panel opens
@@ -121,7 +123,7 @@ export function ItemPicker({
 														item.priceCents != null &&
 														" · "}
 													{item.priceCents != null &&
-														formatPrice(item.priceCents)}
+														formatPrice(item.priceCents, currency)}
 												</span>
 											</label>
 										))}