refactor: 프론트엔드 TypeScript 타입 안전성 및 커스텀 훅 분리

- types/trading.ts: 중앙 타입 정의 (CandleData, Position, Trade 등)
- useMarketData.ts: 실시간 시세 처리 + 500ms 쓰로틀링
- usePortfolioData.ts: React Query 기반 포트폴리오 데이터 훅
- useTradeActions.ts: 매매 실행 액션 훅
- useWebSocket.ts: pong timeout 10초 감지 (좀비 연결 방지)
- TradingChart.tsx: @ts-nocheck 제거, CandleData 타입 적용
- PortfolioPanel/RecommendationPanel: any → 구체적 타입 교체
- Dashboard.tsx: 상태 관리 로직을 커스텀 훅으로 이전

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/hooks/useMarketData.ts

@@ -0,0 +1,65 @@
+import { useEffect, useState, useRef, useCallback } from 'react'
+
+export const useMarketData = (
+    selectedStock: string,
+    portfolio: any[] | undefined
+) => {
+    // Live prices with throttling to prevent excessive re-renders
+    const [livePrices, setLivePrices] = useState<Record<string, number>>({})
+    const [liveQuote, setLiveQuote] = useState<any>(null)
+
+    // Throttle ref: track last update time per stock
+    const lastPriceUpdateRef = useRef<Record<string, number>>({})
+    const throttleDelayMs = 500 // Max 2-3 price updates per second (500ms = 2/sec)
+
+    // Handle market updates (tick data) with throttling
+    const handleMarketUpdate = useCallback((data: unknown) => {
+        const d = data as any
+        if (d?._type === 'tick' && d.stock_code && d.price != null) {
+            const now = Date.now()
+            const lastUpdate =
+                lastPriceUpdateRef.current[d.stock_code] ?? 0
+
+            // Only update if throttle delay has passed
+            if (now - lastUpdate >= throttleDelayMs) {
+                setLivePrices((prev) => ({
+                    ...prev,
+                    [d.stock_code]: d.price,
+                }))
+                lastPriceUpdateRef.current[d.stock_code] = now
+            }
+        } else if (
+            d?._type === 'quote' &&
+            d.stock_code === selectedStock
+        ) {
+            setLiveQuote(d)
+        }
+    }, [selectedStock])
+
+
+    // Initialize live prices from portfolio
+    useEffect(() => {
+        if (!portfolio) return
+        setLivePrices((prev) => {
+            const next = { ...prev }
+            portfolio.forEach((s: any) => {
+                if (s.current_price && !next[s.stock_code]) {
+                    next[s.stock_code] = Number(s.current_price)
+                }
+            })
+            return next
+        })
+    }, [portfolio])
+
+    // Clear live quote when selected stock changes
+    useEffect(() => {
+        setLiveQuote(null)
+    }, [selectedStock])
+
+
+    return {
+        livePrices,
+        liveQuote,
+        handleMarketUpdate,
+    }
+}