Add rqalpha-style position pnl runtime fields

crates/fidc-core/src/engine.rs

@@ -208,6 +208,7 @@ where
 
         for (execution_idx, execution_date) in execution_dates.iter().copied().enumerate() {
             let mut corporate_action_notes = Vec::new();
+            portfolio.begin_trading_day();
             let receivable_report = self.settle_cash_receivables(
                 execution_date,
                 &mut portfolio,