StockTrade 컴포넌트 훅 분리 (Phase 4): 2,788→1,932줄

8개 커스텀 훅으로 state/handler 로직 추출:
- usePortfolio: 포트폴리오 CRUD, 예수금, 브로커 그룹
- useSellHistory: 매도 내역 CRUD, 드로어/폼 상태
- useAiCoach: AI 코치 분석 + 캐시
- useAssetHistory: 자산 추이 차트 데이터
- useMarketContext: VIX/F&G/국채/WTI 시장 데이터
- useAiBalance: AI 모의투자 잔고, 수동 주문
- useReportData: 리포트 정렬, 차트, 집중도 분석
- useAdvisor: 어드바이저 프롬프트 빌더

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

src/pages/stock/hooks/useAiBalance.js

@@ -0,0 +1,84 @@
+import { useState, useCallback, useMemo } from 'react';
+import { getTradeBalance, createTradeOrder } from '../../../api';
+import { getQty, getBuyPrice, getCurrentPrice, getProfitRate, getProfitLoss } from '../stockUtils';
+
+export default function useAiBalance() {
+    const [balance, setBalance] = useState(null);
+    const [balanceLoading, setBalanceLoading] = useState(false);
+    const [balanceError, setBalanceError] = useState('');
+    const [balanceLoaded, setBalanceLoaded] = useState(false);
+
+    const [manualForm, setManualForm] = useState({
+        code: '',
+        qty: 1,
+        price: 0,
+        type: 'buy',
+    });
+    const [manualLoading, setManualLoading] = useState(false);
+    const [manualError, setManualError] = useState('');
+    const [manualResult, setManualResult] = useState(null);
+    const [kisModal, setKisModal] = useState('');
+
+    const loadBalance = useCallback(async () => {
+        setBalanceLoading(true);
+        setBalanceError('');
+        try {
+            const data = await getTradeBalance();
+            setBalance(data);
+            setBalanceLoaded(true);
+        } catch (err) {
+            setBalanceError(err?.message ?? String(err));
+        } finally {
+            setBalanceLoading(false);
+        }
+    }, []);
+
+    const submitManualOrder = async (event) => {
+        event.preventDefault();
+        setManualLoading(true);
+        setManualError('');
+        setManualResult(null);
+        try {
+            const payload = {
+                ticker: manualForm.code.trim(),
+                action: manualForm.type === 'sell' ? 'SELL' : 'BUY',
+                quantity: Number(manualForm.qty),
+                price: Number(manualForm.price),
+            };
+            const result = await createTradeOrder(payload);
+            setManualResult(result ?? { ok: true });
+            if (result?.kis_result !== undefined) {
+                const message =
+                    typeof result.kis_result === 'string'
+                        ? result.kis_result
+                        : JSON.stringify(result.kis_result, null, 2);
+                setKisModal(message);
+            }
+            await loadBalance();
+        } catch (err) {
+            setManualError(err?.message ?? String(err));
+        } finally {
+            setManualLoading(false);
+        }
+    };
+
+    /* derived */
+    const holdings = useMemo(() => {
+        if (!balance) return [];
+        if (Array.isArray(balance.holdings)) return balance.holdings;
+        if (Array.isArray(balance.positions)) return balance.positions;
+        if (Array.isArray(balance.items)) return balance.items;
+        return [];
+    }, [balance]);
+
+    const summary = balance?.summary ?? {};
+    const totalEval = summary.total_eval ?? balance?.total_eval ?? balance?.total_value;
+    const deposit = summary.deposit ?? balance?.deposit ?? balance?.available_cash;
+
+    return {
+        balance, balanceLoading, balanceError, balanceLoaded, loadBalance,
+        holdings, summary, totalEval, deposit,
+        manualForm, setManualForm, manualLoading, manualError, manualResult,
+        kisModal, setKisModal, submitManualOrder,
+    };
+}