feat(chart): MACD(12/26/9) 보조지표 sub-pane + 토글 추가

- EMA + MACD(line/signal/hist) 계산 함수 추가
- MACD 라인(파랑) + Signal 라인(주황) + Histogram (양수=빨강 / 음수=파랑 옅게)
- 별도 lightweight-charts 인스턴스 (RSI 와 동일 패턴, handleScroll/Scale off)
- MA chip 줄에 MACD 토글 chip 추가, 기본 OFF, intraday 에선 숨김
- timeScale 동기화 effect 를 단일 follower 리스트로 일반화 (RSI + MACD 동시 가능)

EMA 헬퍼는 null-tolerant — 결측 시점은 직전 ema 유지. Wilder 가 아닌
표준 EMA (alpha=2/(n+1)) 채택, 트레이딩뷰/Toss 와 동일.

web/components/StockChart.tsx

@@ -4,6 +4,7 @@ import { useEffect, useMemo, useRef, useState } from "react";
 import {
   createChart,
   type CandlestickData,
+  type HistogramData,
   type IChartApi,
   type ISeriesApi,
   type LineData,
@@ -114,6 +115,48 @@ function rsi(closes: (number | null)[], period = 14): (number | null)[] {
   return out;
 }
 
+// 지수이동평균. 첫 유효 값에서 시드 시작, 이후 alpha=2/(n+1) 점화식.
+// null 은 그대로 통과 (해당 시점 계산 안 함, 직전 ema 유지).
+function ema(values: (number | null)[], period: number): (number | null)[] {
+  const out: (number | null)[] = new Array(values.length).fill(null);
+  const alpha = 2 / (period + 1);
+  let cur: number | null = null;
+  for (let i = 0; i < values.length; i++) {
+    const v = values[i];
+    if (v == null) {
+      out[i] = cur;
+      continue;
+    }
+    if (cur == null) cur = v;
+    else cur = alpha * v + (1 - alpha) * cur;
+    out[i] = cur;
+  }
+  return out;
+}
+
+// MACD = EMA12 - EMA26, signal = EMA9(MACD), hist = MACD - signal.
+function macd(
+  closes: (number | null)[],
+  fast = 12,
+  slow = 26,
+  signal = 9,
+): { macd: (number | null)[]; signal: (number | null)[]; hist: (number | null)[] } {
+  const ef = ema(closes, fast);
+  const es = ema(closes, slow);
+  const m: (number | null)[] = ef.map((a, i) => {
+    const b = es[i];
+    if (a == null || b == null) return null;
+    return a - b;
+  });
+  const sig = ema(m, signal);
+  const hist: (number | null)[] = m.map((a, i) => {
+    const b = sig[i];
+    if (a == null || b == null) return null;
+    return a - b;
+  });
+  return { macd: m, signal: sig, hist };
+}
+
 export function StockChart({ chart, prediction }: Props) {
   const containerRef = useRef<HTMLDivElement | null>(null);
   const chartRef = useRef<IChartApi | null>(null);
@@ -124,14 +167,22 @@ export function StockChart({ chart, prediction }: Props) {
   const rsiContainerRef = useRef<HTMLDivElement | null>(null);
   const rsiChartRef = useRef<IChartApi | null>(null);
   const rsiSeriesRef = useRef<ISeriesApi<"Line"> | null>(null);
+  // MACD 보조차트 — RSI 와 같은 패턴 (별 인스턴스, 단방향 sync).
+  const macdContainerRef = useRef<HTMLDivElement | null>(null);
+  const macdChartRef = useRef<IChartApi | null>(null);
+  const macdLineRef = useRef<ISeriesApi<"Line"> | null>(null);
+  const macdSignalRef = useRef<ISeriesApi<"Line"> | null>(null);
+  const macdHistRef = useRef<ISeriesApi<"Histogram"> | null>(null);
 
   // 토글 상태 — 기본 MA20 만 ON. 사용자 컨트롤이 너무 시끄럽지 않게.
   const [active, setActive] = useState<Set<SmaWindow>>(() => new Set<SmaWindow>([20]));
   const [rsiOn, setRsiOn] = useState(false);
+  const [macdOn, setMacdOn] = useState(false);
 
   const isIntraday = chart.interval === "10m";
   const showSma = !isIntraday; // 10분봉에선 의미 적음 — UI 도 숨김.
   const showRsi = !isIntraday && rsiOn;
+  const showMacd = !isIntraday && macdOn;
 
   // chart 생성 — interval 바뀌면 timeVisible 토글을 위해 재생성.
   useEffect(() => {
@@ -368,24 +419,109 @@ export function StockChart({ chart, prediction }: Props) {
     rsiSeriesRef.current.setData(data);
   }, [closes, chart, showRsi]);
 
-  // 메인 ↔ RSI timeScale 동기화. 메인이 source, RSI 가 follower.
+  // MACD 보조 차트 생성/제거.
-  // 핸들 스크롤은 RSI 쪽 꺼져 있어 단방향이면 충분.
+  useEffect(() => {
+    if (!showMacd || !macdContainerRef.current) return;
+    const c = createChart(macdContainerRef.current, {
+      layout: { background: { color: "transparent" }, textColor: "#cbd5e1" },
+      grid: {
+        vertLines: { color: "#1f2937" },
+        horzLines: { color: "#1f2937" },
+      },
+      rightPriceScale: {
+        borderColor: "#374151",
+        scaleMargins: { top: 0.1, bottom: 0.1 },
+      },
+      timeScale: {
+        borderColor: "#374151",
+        timeVisible: false,
+        secondsVisible: false,
+      },
+      autoSize: true,
+      crosshair: { mode: 1 },
+      handleScroll: false,
+      handleScale: false,
+    });
+    const hist = c.addHistogramSeries({
+      priceLineVisible: false,
+      lastValueVisible: false,
+      priceFormat: { type: "price", precision: 2, minMove: 0.01 },
+    });
+    const macdLine = c.addLineSeries({
+      color: "#60a5fa",
+      lineWidth: 1,
+      priceLineVisible: false,
+      lastValueVisible: true,
+      title: "MACD",
+      priceFormat: { type: "price", precision: 2, minMove: 0.01 },
+    });
+    const signalLine = c.addLineSeries({
+      color: "#fb923c",
+      lineWidth: 1,
+      priceLineVisible: false,
+      lastValueVisible: true,
+      title: "Signal",
+      priceFormat: { type: "price", precision: 2, minMove: 0.01 },
+    });
+    macdChartRef.current = c;
+    macdHistRef.current = hist;
+    macdLineRef.current = macdLine;
+    macdSignalRef.current = signalLine;
+    return () => {
+      c.remove();
+      macdChartRef.current = null;
+      macdHistRef.current = null;
+      macdLineRef.current = null;
+      macdSignalRef.current = null;
+    };
+  }, [showMacd]);
+
+  // MACD 데이터 push.
+  useEffect(() => {
+    const hSeries = macdHistRef.current;
+    const mSeries = macdLineRef.current;
+    const sSeries = macdSignalRef.current;
+    if (!hSeries || !mSeries || !sSeries) return;
+    const { macd: m, signal: sig, hist } = macd(closes, 12, 26, 9);
+    const mLine: LineData[] = [];
+    const sLine: LineData[] = [];
+    const hBars: HistogramData[] = [];
+    for (let i = 0; i < closes.length; i++) {
+      const t = isoToUtcTs(chart.ohlcv[i].date);
+      if (m[i] != null) mLine.push({ time: t, value: m[i] as number });
+      if (sig[i] != null) sLine.push({ time: t, value: sig[i] as number });
+      if (hist[i] != null) {
+        const h = hist[i] as number;
+        // 한국 관행: 양수 막대=상승=빨강, 음수=하락=파랑. 컬러 옅게 (배경 톤).
+        hBars.push({ time: t, value: h, color: h >= 0 ? "#ef444488" : "#3b82f688" });
+      }
+    }
+    hSeries.setData(hBars);
+    mSeries.setData(mLine);
+    sSeries.setData(sLine);
+  }, [closes, chart, showMacd]);
+
+  // 메인 ↔ 보조패널 timeScale 단방향 동기화. RSI/MACD 둘 다 처리.
   useEffect(() => {
     const main = chartRef.current;
-    const sub = rsiChartRef.current;
+    if (!main) return;
-    if (!main || !sub || !showRsi) return;
+    const followers: IChartApi[] = [];
+    if (showRsi && rsiChartRef.current) followers.push(rsiChartRef.current);
+    if (showMacd && macdChartRef.current) followers.push(macdChartRef.current);
+    if (!followers.length) return;
     const handler = (range: LogicalRange | null) => {
       if (!range) return;
-      sub.timeScale().setVisibleLogicalRange(range);
+      for (const f of followers) f.timeScale().setVisibleLogicalRange(range);
     };
-    // 초기 동기화.
     const initial = main.timeScale().getVisibleLogicalRange();
-    if (initial) sub.timeScale().setVisibleLogicalRange(initial);
+    if (initial) {
+      for (const f of followers) f.timeScale().setVisibleLogicalRange(initial);
+    }
     main.timeScale().subscribeVisibleLogicalRangeChange(handler);
     return () => {
       main.timeScale().unsubscribeVisibleLogicalRangeChange(handler);
     };
-  }, [showRsi, chart]);
+  }, [showRsi, showMacd, chart]);
 
   const toggle = (w: SmaWindow) => {
     setActive((cur) => {
@@ -440,6 +576,23 @@ export function StockChart({ chart, prediction }: Props) {
             />
             RSI
           </button>
+          <button
+            type="button"
+            onClick={() => setMacdOn((v) => !v)}
+            className={`flex items-center gap-1 rounded-full border px-2 py-0.5 text-[10px] transition ${
+              macdOn
+                ? "border-zinc-600 bg-zinc-800/80 text-zinc-100"
+                : "border-zinc-800 bg-transparent text-zinc-500 hover:text-zinc-300"
+            }`}
+            aria-pressed={macdOn}
+            title="MACD (12/26/9) — 추세 전환 신호"
+          >
+            <span
+              className="inline-block h-2 w-2 rounded-full"
+              style={{ backgroundColor: macdOn ? "#60a5fa" : "transparent", border: "1px solid #60a5fa" }}
+            />
+            MACD
+          </button>
         </div>
       )}
       <div className="h-[460px] w-full">
@@ -450,6 +603,11 @@ export function StockChart({ chart, prediction }: Props) {
           <div ref={rsiContainerRef} className="h-full w-full" />
         </div>
       )}
+      {showMacd && (
+        <div className="mt-2 h-[110px] w-full border-t border-zinc-800 pt-1">
+          <div ref={macdContainerRef} className="h-full w-full" />
+        </div>
+      )}
       {prediction?.found && !isIntraday && (
         <div className="mt-1 flex items-center justify-end gap-2 px-2 text-[11px] text-zinc-500">
           <span className="inline-block h-2 w-2 rounded-sm bg-rose-300" />