feat(targets): price target/stop simulator with chart overlay lines

- New lib/targets.ts: per-code localStorage (key `targets:<code>`) with
  read/write/clear; rejects non-positive/non-finite values.
- New PriceTargets sidebar panel: 목표가/손절가 inputs, live %-from-current
  preview (rose=up, sky=down), save/clear actions.
- StockChart accepts optional `targets` prop and draws dashed horizontal
  price lines on the candle series (rose=target, sky=stop) with axis labels.
- Page loads saved targets on mount/code-change and re-renders chart on save.

Also fixes view-counter dedupe caveat from reviewer: split into
wasRecordedToday() + markRecorded(); the page now marks localStorage only
after POST /api/views succeeds, so a failed POST stays retryable on the
next visit instead of being silently swallowed for the day.

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

web/app/[code]/page.tsx

@@ -14,6 +14,7 @@ import { PeriodReturns } from "../../components/PeriodReturns";
 import { PeriodTabs, periodSpec, type Period } from "../../components/PeriodTabs";
 import { PredictionPanel } from "../../components/PredictionPanel";
 import { PriceHero } from "../../components/PriceHero";
+import { PriceTargets } from "../../components/PriceTargets";
 import { RelatedStocks } from "../../components/RelatedStocks";
 import { StarButton } from "../../components/StarButton";
 import { StockChart } from "../../components/StockChart";
@@ -21,7 +22,8 @@ import { SymbolSidebar } from "../../components/SymbolSidebar";
 import { TradingValuePanel } from "../../components/TradingValuePanel";
 import { api, type ChartPayload, type LatestPredictionResponse } from "../../lib/api";
 import { recent } from "../../lib/recent";
-import { shouldRecordView } from "../../lib/views";
+import { readTargets, type Targets } from "../../lib/targets";
+import { markRecorded, wasRecordedToday } from "../../lib/views";
 
 export default function CodePage({ params }: { params: { code: string } }) {
   const { code } = params;
@@ -30,6 +32,7 @@ export default function CodePage({ params }: { params: { code: string } }) {
   const [err, setErr] = useState<string | null>(null);
   const [period, setPeriod] = useState<Period>("3M");
   const [viewsToday, setViewsToday] = useState<number | null>(null);
+  const [targets, setTargets] = useState<Targets>({});
 
   const spec = periodSpec(period);
   const isIntraday = spec.interval === "10m";
@@ -49,11 +52,17 @@ export default function CodePage({ params }: { params: { code: string } }) {
     const apply = (n: number) => {
       if (alive) setViewsToday(n);
     };
-    if (shouldRecordView(code)) {
-      api.recordView(code).then((r) => apply(r.today_views)).catch(() => {
-        // POST 실패 시 GET 한 번 시도 (혹시 다른 사용자 카운트라도 보여줌).
-        api.views(code).then((r) => apply(r.today_views)).catch(() => {});
-      });
+    if (!wasRecordedToday(code)) {
+      api.recordView(code)
+        .then((r) => {
+          // POST 성공 후에만 mark — 실패 시 다음 방문에 다시 시도 가능.
+          markRecorded(code);
+          apply(r.today_views);
+        })
+        .catch(() => {
+          // POST 실패 시 GET 한 번 시도 (혹시 다른 사용자 카운트라도 보여줌).
+          api.views(code).then((r) => apply(r.today_views)).catch(() => {});
+        });
     } else {
       api.views(code).then((r) => apply(r.today_views)).catch(() => {});
     }
@@ -62,6 +71,11 @@ export default function CodePage({ params }: { params: { code: string } }) {
     };
   }, [code]);
 
+  // 저장된 목표가/손절가 — 마운트 + 종목 전환 시 localStorage 에서 로드.
+  useEffect(() => {
+    setTargets(readTargets(code));
+  }, [code]);
+
   useEffect(() => {
     let alive = true;
     setErr(null);
@@ -169,7 +183,7 @@ export default function CodePage({ params }: { params: { code: string } }) {
           />
           <div className="grid gap-6 lg:grid-cols-[1fr_280px]">
             <div>
-              <StockChart chart={chart} prediction={prediction} />
+              <StockChart chart={chart} prediction={prediction} targets={targets} />
               {isIntraday && chart.intraday_status && (
                 <div className="mt-2 text-right text-[11px] text-zinc-500">
                   실시간 10분봉 · 60초 갱신 · [{chart.intraday_status}]
@@ -182,6 +196,7 @@ export default function CodePage({ params }: { params: { code: string } }) {
             <div className="space-y-4">
               <SymbolSidebar code={code} />
               <OrderbookPanel code={code} />
+              <PriceTargets code={code} current={current} onChange={setTargets} />
               <AlertsPanel code={code} name={chart?.name} current={current} />
               <RelatedStocks code={code} />
             </div>