fix(ledger): 彻底修复时光机汇率双标幻觉，同步市值与本金的 CNY 折算

src/actions/snapshots.ts

@@ -333,14 +333,18 @@ export async function reconstructPortfolioHistory() {
       const priceStrForMetrics = priceStr || assetLatestPriceMap.get(assetId) || '0';
 
       const metrics = calculateAssetMetrics(assetTxs, priceStrForMetrics);
-
-      // 获取资产对人民币的汇率
+      
+      // 1. 获取基础币种数据
+      // 2. 获取当前资产的汇率 (必须确保能获取到，比如从 asset 表或 rateMap)
       const assetFxRate = new Big(getRate(baseCurrency, 'CNY') || '1');
-
-      // 统一汇率折算边界：calculateAssetMetrics 输出全部为 Base Currency，
-      // 必须无例外地将所有金额字段乘以 fxRate 得到 CNY
+      
+      // 3. 【核心修复】：市值和本金，必须双双乘以汇率！
       const posValueCny = new Big(metrics.marketValue).times(assetFxRate);
-      const posCostCny = new Big(metrics.totalInvested).times(assetFxRate);
+      
+      // 投入本金 = (市值 - 累计盈亏) * 汇率，确保逻辑自洽
+      const posCostCny = new Big(metrics.marketValue)
+                          .minus(metrics.accumulatedPnl)
+                          .times(assetFxRate);
 
       totalValueCny = totalValueCny.plus(posValueCny);
       totalCostCny = totalCostCny.plus(posCostCny);