feat(market): add 24h crypto sparkline chart with CoinGecko history and resilient fallback

components/converter/converter-card.tsx

@@ -12,6 +12,7 @@ import {
 } from "lucide-react";
 
 import { CurrencyIcon } from "@/components/converter/currency-icon";
+import { PriceSparkline } from "@/components/converter/price-sparkline";
 import { CurrencySelect } from "@/components/converter/currency-select";
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
@@ -550,6 +551,12 @@ export function ConverterCard({
               </p>
             ) : null}
 
+            <PriceSparkline
+              points={marketData?.priceHistory24h ?? []}
+              isLoading={isMarketLoading && !marketData}
+              className="mt-3"
+            />
+
             <div className="mt-3 grid gap-2 sm:grid-cols-2 lg:grid-cols-4">
               <div className="rounded-lg border border-border/60 bg-background/60 p-3">
                 <p className="text-xs uppercase tracking-[0.1em] text-muted-foreground">