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/components/PortfolioPanel.tsx

@@ -1,8 +1,9 @@
 import React from 'react'
 import { Activity } from 'lucide-react'
+import { Position } from '../types/trading'
 
 interface PortfolioPanelProps {
-    portfolio: any[] | undefined
+    portfolio: Position[] | undefined
     livePrices: Record<string, number> | undefined
     selectedStock: string
     onSelectStock: (code: string) => void
@@ -31,7 +32,7 @@ const PortfolioPanel = React.memo(({
             </div>
             <div className="divide-y divide-gray-700/50 overflow-y-auto custom-scrollbar flex-1">
                 {portfolio && portfolio.length > 0 ? (
-                    portfolio.map((stock: any) => {
+                    portfolio.map((stock: Position) => {
                         const currentPrice = livePrices?.[stock.stock_code] ?? Number(stock.current_price || 0)
                         const avgPrice = Number(stock.average_price || 0)
                         const quantity = Number(stock.quantity || 0)
@@ -40,13 +41,14 @@ const PortfolioPanel = React.memo(({
                             ? ((currentPrice - avgPrice) / avgPrice) * 100
                             : Number(stock.profit_loss_rate || 0)
 
-                        const handleSellClick = async (e: React.MouseEvent) => {
+                        const handleSellClick = async (e: React.MouseEvent<HTMLButtonElement>) => {
                             e.stopPropagation()
 
                             try {
                                 await onSell(stock.stock_code, stock.stock_name, quantity)
-                            } catch (error: any) {
-                                alert(`매도 실패: ${error.response?.data?.detail || error.message}`)
+                            } catch (error: unknown) {
+                                const err = error as any;
+                                alert(`매도 실패: ${err.response?.data?.detail || err.message}`)
                             }
                         }