feat: add pyside6 holdings gui

tests/test_ui.py

@@ -0,0 +1,31 @@
+from decimal import Decimal
+
+
+def test_formatters_render_money_percent_and_empty_values():
+    from grid_trading.ui.formatters import format_money, format_percent, format_price, format_quantity
+
+    assert format_money(Decimal("1234.5")) == "1,234.50"
+    assert format_price(Decimal("3.956")) == "3.96"
+    assert format_percent(Decimal("0.1234")) == "12.34%"
+    assert format_quantity(1200) == "1,200"
+    assert format_money(None) == "-"
+
+
+def test_main_window_can_be_constructed_offscreen(tmp_path, monkeypatch):
+    monkeypatch.setenv("QT_QPA_PLATFORM", "offscreen")
+
+    from PySide6.QtWidgets import QApplication
+
+    from grid_trading.services.trading_service import TradingService
+    from grid_trading.ui.main_window import MainWindow
+
+    app = QApplication.instance() or QApplication([])
+    service = TradingService(tmp_path / "grid.db")
+    window = MainWindow(service)
+
+    assert window.windowTitle() == "Grid Trading Manager"
+    assert window.holdings_table.columnCount() > 0
+
+    window.close()
+    service.close()
+    app.processEvents()