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/SetupCard.tsx

@@ -1,4 +1,5 @@
 import { Link } from "@tanstack/react-router";
+import { useCurrency } from "../hooks/useCurrency";
 import { useWeightUnit } from "../hooks/useWeightUnit";
 import { formatPrice, formatWeight } from "../lib/formatters";
 
@@ -18,6 +19,7 @@ export function SetupCard({
 	totalCost,
 }: SetupCardProps) {
 	const unit = useWeightUnit();
+	const currency = useCurrency();
 	return (
 		<Link
 			to="/setups/$setupId"
@@ -35,7 +37,7 @@ export function SetupCard({
 					{formatWeight(totalWeight, unit)}
 				</span>
 				<span className="inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium bg-green-50 text-green-500">
-					{formatPrice(totalCost)}
+					{formatPrice(totalCost, currency)}
 				</span>
 			</div>
 		</Link>