feat: 보유종목 탭 현재가 표시 + 빈상태 문구 수정

- HoldingCard 헤더에 h.close 현재가 표시 (null guard, toLocaleString 천단위)
- Stock.css에 .hi-card__close 추가 (#94a3b8, 11px, margin-right 4px)
- !loading && !error && !data 분기 메시지 '데이터를 불러오는 중입니다.' → '데이터가 없습니다.'

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/pages/stock/Stock.css

@@ -3117,6 +3117,12 @@
 .hi-card__pnl.is-up   { color: #22c55e; }
 .hi-card__pnl.is-down { color: #ef4444; }
 
+.hi-card__close {
+    font-size: 11px;
+    color: #94a3b8;
+    margin-right: 4px;
+}
+
 .hi-card__reasons {
     font-size: 12px;
     color: #94a3b8;

src/pages/stock/components/HoldingsIntelTab.jsx

@@ -46,6 +46,9 @@ const HoldingCard = ({ h }) => {
                 </span>
                 <strong className="hi-card__name">{h.name || h.ticker}</strong>
                 <span className="hi-card__ticker">{h.ticker}</span>
+                {h.close != null && (
+                    <span className="hi-card__close">{h.close.toLocaleString()}원</span>
+                )}
                 <span className={`hi-card__pnl ${(h.pnl_rate ?? 0) >= 0 ? 'is-up' : 'is-down'}`}>
                     {fmtRate(h.pnl_rate)}
                 </span>
@@ -113,7 +116,7 @@ const HoldingsIntelTab = () => {
             {error && <p className="stock-error">{error}</p>}
 
             {!loading && !error && !data && (
-                <p className="stock-empty">데이터를 불러오는 중입니다.</p>
+                <p className="stock-empty">데이터가 없습니다.</p>
             )}
 
             {!loading && data && (