feat(ui): 기간 수익률 + 거래주체 순매수 패널

- PeriodReturns: chart.ohlcv 종가로 1주/1개월/3개월/6개월/1년/전체 수익률 그리드
- TradingValuePanel: chart.trading_value 외국인/기관/개인 최근 5일 표 (억원 단위)
- [code]/page.tsx 레이아웃 재배치: 수익률 → 거래주체+메트릭 → 뉴스+공시

백엔드 변경 없음 — 기존 ChartPayload 의 미사용 시리즈를 재활용.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/app/[code]/page.tsx

@@ -5,6 +5,7 @@ import { useEffect, useMemo, useState } from "react";
 import { DisclosuresPanel } from "../../components/DisclosuresPanel";
 import { MetricsPanel } from "../../components/MetricsPanel";
 import { NewsList } from "../../components/NewsList";
+import { PeriodReturns } from "../../components/PeriodReturns";
 import { PeriodTabs, periodSpec, type Period } from "../../components/PeriodTabs";
 import { PredictionPanel } from "../../components/PredictionPanel";
 import { PriceHero } from "../../components/PriceHero";
@@ -12,6 +13,7 @@ import { RelatedStocks } from "../../components/RelatedStocks";
 import { StarButton } from "../../components/StarButton";
 import { StockChart } from "../../components/StockChart";
 import { SymbolSidebar } from "../../components/SymbolSidebar";
+import { TradingValuePanel } from "../../components/TradingValuePanel";
 import { api, type ChartPayload, type LatestPredictionResponse } from "../../lib/api";
 
 export default function CodePage({ params }: { params: { code: string } }) {
@@ -138,11 +140,15 @@ export default function CodePage({ params }: { params: { code: string } }) {
               <RelatedStocks code={code} />
             </div>
           </div>
-          <div className="mt-6 grid gap-6 md:grid-cols-2">
-            <MetricsPanel code={code} />
-            <NewsList code={code} />
-          </div>
           <div className="mt-6">
+            <PeriodReturns ohlcv={chart.ohlcv} />
+          </div>
+          <div className="mt-6 grid gap-6 md:grid-cols-2">
+            <TradingValuePanel data={chart.trading_value} />
+            <MetricsPanel code={code} />
+          </div>
+          <div className="mt-6 grid gap-6 md:grid-cols-2">
+            <NewsList code={code} />
             <DisclosuresPanel code={code} />
           </div>
         </>