Trades: an open position shows no close price or P&L

Vest's position history gives an open position a placeholder close price
and a $0 P&L (290.25 on an NDX short at 29,538.96). Only a closed
position keeps them now — in the parser, in the stored row (a placeholder
already stored is cleared on the next read) and in the API.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/check-vest.mjs

@@ -293,6 +293,13 @@ test('parseHistoryPosition: open, snake_case, seconds, and junk', () => {
     assert.equal(open.openedAt, 1793065590000);
     assert.equal(open.closedAt, null);
     assert.equal(open.closeReason, null);
+    const held = parseHistoryPosition({
+        positionId: 'p3', symbol: 'NDX-USD-PERP', side: 'short', quantity: '85.7363', openPrice: '29538.96', closePrice: '290.25',
+        pnl: '0.0', fee: '63.314059', funding: '0.0', openDate: 1793065422000, closeDate: null,
+    });
+    assert.equal(held.closePrice, null, "an open position's placeholder close price is dropped");
+    assert.equal(held.pnl, null, 'and its $0 P&L');
+    assert.equal(held.fee, 63.314059, 'its entry fee is real');
     assert.equal(parseHistoryPosition({ symbol: 'GC-PERP', openDate: 1 }), null, 'no id');
     assert.equal(parseHistoryPosition({ positionId: 'p2', symbol: 'GC-PERP' }), null, 'no open time');
     assert.equal(parseHistoryPosition(null), null);