style(ui): 规范红涨绿跌视觉习惯，并移除盈亏数值多余的正号

app/dashboard/page.tsx

@@ -57,8 +57,7 @@ function formatPnl(value: string, percent: string, baseCurrency: string): { text
   const symbol = getCurrencySymbol(baseCurrency);
   const absValue = new Big(value).abs().toFixed(2);
   const absPercent = new Big(percent).abs().toFixed(2);
-  const sign = isPositive ? '+' : '';
-  const text = `${sign}${symbol}${absValue} (${sign}${absPercent}%)`;
+  const text = `${symbol}${absValue} (${absPercent}%)`;
   const className = isPositive ? 'text-red-500' : 'text-green-500';
   return { text, className };
 }
@@ -157,14 +156,14 @@ export default function DashboardPage() {
           <div className="mt-3 flex flex-wrap gap-4">
             <div className="flex items-center gap-2">
               <span className="text-sm text-muted-foreground">持仓盈亏:</span>
-              <span className={`text-lg font-semibold ${unrealizedIsPositive ? 'text-green-500' : 'text-red-500'}`}>
-                {unrealizedIsPositive ? '+' : ''}{formattedUnrealized}
+              <span className={`text-lg font-semibold ${unrealizedIsPositive ? 'text-red-500' : 'text-green-500'}`}>
+                {formattedUnrealized}
               </span>
             </div>
             <div className="flex items-center gap-2">
               <span className="text-sm text-muted-foreground">总盈亏:</span>
-              <span className={`text-lg font-semibold ${totalPnlIsPositive ? 'text-green-500' : 'text-red-500'}`}>
-                {totalPnlIsPositive ? '+' : ''}{formattedTotalPnl}
+              <span className={`text-lg font-semibold ${totalPnlIsPositive ? 'text-red-500' : 'text-green-500'}`}>
+                {formattedTotalPnl}
               </span>
             </div>
           </div>