feat(stock): 포트폴리오 매입가/평균단가 분리 + 총 매입 금액 반영

- 기존 카드의 "매입가" → "평균단가" (avg_price) 로 라벨 변경
- 신규 "매입가" (purchase_price) 컬럼 추가. 추가/수정 폼에 입력 필드 노출
  (미입력 시 평균단가 값으로 자동 설정)
- 브로커별 총 매입 금액은 purchase_price × quantity 합계 기준
- 손익/수익률은 평균단가(avg_price) 기준 유지

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

src/pages/stock/components/PortfolioTab.jsx

@@ -96,7 +96,7 @@ const PortfolioTab = ({ pf, asset, handleSell, handleSaveSnapshot }) => (
                         />
                     </label>
                     <label>
-                        평균 매입가 (원)
+                        평균단가 (원)
                         <input
                             type="number"
                             min={0}
@@ -108,6 +108,19 @@ const PortfolioTab = ({ pf, asset, handleSell, handleSaveSnapshot }) => (
                             required
                         />
                     </label>
+                    <label>
+                        매입가 (원)
+                        <input
+                            type="number"
+                            min={0}
+                            step={1}
+                            value={pf.addForm.purchase_price}
+                            onChange={(e) =>
+                                pf.setAddForm((p) => ({ ...p, purchase_price: e.target.value }))
+                            }
+                            placeholder="미입력 시 평균단가로 자동 설정"
+                        />
+                    </label>
                     <button
                         className="button primary"
                         type="submit"
@@ -435,7 +448,7 @@ const PortfolioTab = ({ pf, asset, handleSell, handleSaveSnapshot }) => (
                                                     />
                                                 </label>
                                                 <label>
-                                                    평균매입가
+                                                    평균단가
                                                     <input
                                                         type="number"
                                                         min={0}
@@ -448,6 +461,20 @@ const PortfolioTab = ({ pf, asset, handleSell, handleSaveSnapshot }) => (
                                                         }
                                                     />
                                                 </label>
+                                                <label>
+                                                    매입가
+                                                    <input
+                                                        type="number"
+                                                        min={0}
+                                                        value={pf.editForm.purchase_price ?? ''}
+                                                        onChange={(e) =>
+                                                            pf.setEditForm((p) => ({
+                                                                ...p,
+                                                                purchase_price: Number(e.target.value),
+                                                            }))
+                                                        }
+                                                    />
+                                                </label>
                                             </div>
                                             <div className="pf-edit-actions">
                                                 <button
@@ -480,9 +507,13 @@ const PortfolioTab = ({ pf, asset, handleSell, handleSaveSnapshot }) => (
                                                 <strong>{formatNumber(item.quantity)}</strong>
                                             </div>
                                             <div className="stock-holdings__metric">
-                                                <span>매입가</span>
+                                                <span>평균단가</span>
                                                 <strong>{formatNumber(item.avg_price)}</strong>
                                             </div>
+                                            <div className="stock-holdings__metric">
+                                                <span>매입가</span>
+                                                <strong>{formatNumber(item.purchase_price ?? item.avg_price)}</strong>
+                                            </div>
                                             <div className="stock-holdings__metric">
                                                 <span>현재가</span>
                                                 <strong className={item.current_price == null ? 'pf-null-price' : ''}>

src/pages/stock/hooks/usePortfolio.js

@@ -70,14 +70,19 @@ export default function usePortfolio() {
     }, [brokerGroups]);
 
     const getBrokerSummary = (items) => {
-        let totalBuy = 0, totalEvalAmt = 0, hasNullPrice = false;
+        // totalBuy: 요약 표시용 (매입가 purchase_price 기준)
+        // totalCostBasis: 손익 계산용 (평균단가 avg_price 기준)
+        let totalBuy = 0, totalCostBasis = 0, totalEvalAmt = 0, hasNullPrice = false;
         for (const item of items) {
-            totalBuy += (item.avg_price ?? 0) * (item.quantity ?? 0);
+            const qty = item.quantity ?? 0;
+            const purchase = item.purchase_price ?? item.avg_price ?? 0;
+            totalBuy += purchase * qty;
+            totalCostBasis += (item.avg_price ?? 0) * qty;
             if (item.eval_amount != null) totalEvalAmt += item.eval_amount;
             else hasNullPrice = true;
         }
-        const totalProfit = totalEvalAmt - totalBuy;
+        const totalProfit = totalEvalAmt - totalCostBasis;
-        const totalProfitRate = totalBuy > 0 ? (totalProfit / totalBuy) * 100 : 0;
+        const totalProfitRate = totalCostBasis > 0 ? (totalProfit / totalCostBasis) * 100 : 0;
         return { totalBuy, totalEval: totalEvalAmt, totalProfit, totalProfitRate, hasNullPrice };
     };
 
@@ -108,6 +113,9 @@ export default function usePortfolio() {
                 name: addForm.name.trim(),
                 quantity: Number(addForm.quantity),
                 avg_price: Number(addForm.avg_price),
+                purchase_price: addForm.purchase_price === '' || addForm.purchase_price == null
+                    ? Number(addForm.avg_price)
+                    : Number(addForm.purchase_price),
             });
             setAddForm({ ...emptyPortfolioForm });
             setAddFormOpen(false);
@@ -121,7 +129,13 @@ export default function usePortfolio() {
 
     const handleEditStart = (item) => {
         setEditingId(item.id);
-        const data = { quantity: item.quantity, avg_price: item.avg_price, broker: item.broker, name: item.name };
+        const data = {
+            quantity: item.quantity,
+            avg_price: item.avg_price,
+            purchase_price: item.purchase_price ?? item.avg_price,
+            broker: item.broker,
+            name: item.name,
+        };
         setEditForm(data);
         editOrigRef.current = { ...data };
     };

src/pages/stock/stockUtils.js

@@ -95,6 +95,7 @@ export const emptyPortfolioForm = {
     name: '',
     quantity: '',
     avg_price: '',
+    purchase_price: '',
 };
 
 /* ── empty sell-history form ─────────────────────────────────────── */