fix: ensure all timestamps use UTC timezone

- Add NowFunc to GORM config for UTC auto-generated timestamps
- Add .UTC() to all time.UnixMilli() calls in trader files
- Add .UTC() to all time.Now() calls in store and api files
- Fix TypeScript unused imports in frontend

trader/okx_order_sync.go

@@ -133,7 +133,7 @@ func (t *OKXTrader) GetTrades(startTime time.Time, limit int) ([]OKXTrade, error
 			FillQtyBase: fillQtyBase,
 			Fee:         -fee, // OKX returns negative fee
 			FeeAsset:    fill.FeeCcy,
-			ExecTime:    time.UnixMilli(ts),
+			ExecTime:    time.UnixMilli(ts).UTC(),
 			IsMaker:     fill.ExecType == "M",
 			OrderType:   "MARKET",
 			OrderAction: orderAction,
@@ -197,7 +197,8 @@ func (t *OKXTrader) SyncOrdersFromOKX(traderID string, exchangeID string, exchan
 		// Normalize side for storage
 		side := strings.ToUpper(trade.Side)
 
-		// Create order record
+		// Create order record - use UTC time to avoid timezone issues
+		execTimeUTC := trade.ExecTime.UTC()
 		orderRecord := &store.TraderOrder{
 			TraderID:        traderID,
 			ExchangeID:      exchangeID,   // UUID
@@ -214,9 +215,9 @@ func (t *OKXTrader) SyncOrdersFromOKX(traderID string, exchangeID string, exchan
 			FilledQuantity:  trade.FillQtyBase,
 			AvgFillPrice:    trade.FillPrice,
 			Commission:      trade.Fee,
-			FilledAt:        trade.ExecTime,
-			CreatedAt:       trade.ExecTime,
-			UpdatedAt:       trade.ExecTime,
+			FilledAt:        execTimeUTC,
+			CreatedAt:       execTimeUTC,
+			UpdatedAt:       execTimeUTC,
 		}
 
 		// Insert order record
@@ -225,7 +226,7 @@ func (t *OKXTrader) SyncOrdersFromOKX(traderID string, exchangeID string, exchan
 			continue
 		}
 
-		// Create fill record
+		// Create fill record - use UTC time
 		fillRecord := &store.TraderFill{
 			TraderID:        traderID,
 			ExchangeID:      exchangeID,   // UUID
@@ -242,7 +243,7 @@ func (t *OKXTrader) SyncOrdersFromOKX(traderID string, exchangeID string, exchan
 			CommissionAsset: trade.FeeAsset,
 			RealizedPnL:     0, // OKX fills don't include PnL per trade
 			IsMaker:         trade.IsMaker,
-			CreatedAt:       trade.ExecTime,
+			CreatedAt:       execTimeUTC,
 		}
 
 		if err := orderStore.CreateFill(fillRecord); err != nil {