style: 委托行展开箭头改为大号SVG（14px绿色+旋转动画）

src/client/views/TradeRecordsTab.jsx

@@ -277,7 +277,34 @@ function OrderRows({ order, expanded, onToggle }) {
           background: expanded ? '#f5f5f5' : 'transparent',
         }}
       >
-        <td style={tdStyle}>{hasTrades ? (expanded ? '▾' : '▸') : <span style={{ color: '#ccc' }}>·</span>}</td>
+        <td style={{ ...tdStyle, textAlign: 'center', width: 28 }}>
+        {hasTrades ? (
+          <svg
+            width="14"
+            height="14"
+            viewBox="0 0 14 14"
+            style={{
+              display: 'inline-block',
+              transition: 'transform .15s ease',
+              transform: expanded ? 'rotate(90deg)' : 'rotate(0deg)',
+              cursor: 'pointer',
+              color: '#2e7d32',
+              verticalAlign: 'middle',
+            }}
+          >
+            <path
+              d="M4.5 2.5 L9.5 7 L4.5 11.5"
+              fill="none"
+              stroke="currentColor"
+              strokeWidth="2"
+              strokeLinecap="round"
+              strokeLinejoin="round"
+            />
+          </svg>
+        ) : (
+          <span style={{ color: '#ccc', fontSize: 10 }}>·</span>
+        )}
+      </td>
         <td style={tdStyle}>{fmtTime(order.insertTime)}</td>
         <td style={tdStyle}>{order.code}</td>
         <td style={tdStyle}>{order.name}</td>