feat(selection): show gold brick chart below volume in stock detail panel

Add an optional brick_chart series to the selection chart API, computed
from the shared gold-brick formula when strategy=gold_brick, and render
a fourth grid with red/green brick bars between the volume and J grids.

zhixing-server/tests/unit/selection/test_chart.py

@@ -9,6 +9,9 @@ from zhixing_server.modules.selection.application.chart import (
     GetSelectionChart,
     SelectionChartNotFound,
 )
+from zhixing_server.modules.selection.domain.gold_brick import (
+    prepare_gold_brick_indicators,
+)
 from zhixing_server.modules.selection.domain.indicators import (
     compute_kdj,
     compute_zhixing_lines,
@@ -100,6 +103,36 @@ def test_chart_filters_future_rows_and_preserves_nullable_points() -> None:
     assert chart.points[3].j is None
 
 
+def test_chart_skips_brick_series_by_default_and_computes_on_request() -> None:
+    history = _history(260)
+    reader = FakeReader(history)
+    target = history.bars[-1].trade_date
+
+    default_chart = GetSelectionChart(reader).execute(history.ts_code, target)
+    assert all(point.brick_chart is None for point in default_chart.points)
+
+    brick_chart = GetSelectionChart(reader).execute(
+        history.ts_code,
+        target,
+        include_brick_chart=True,
+    )
+
+    frame = pd.DataFrame(
+        {
+            "trade_date": [bar.trade_date for bar in history.bars],
+            "open": [bar.open for bar in history.bars],
+            "high": [bar.high for bar in history.bars],
+            "low": [bar.low for bar in history.bars],
+            "close": [bar.close for bar in history.bars],
+            "volume": [bar.volume for bar in history.bars],
+        }
+    )
+    expected = prepare_gold_brick_indicators(frame, history.ts_code)["brick_chart"]
+    assert brick_chart.points[-1].brick_chart == pytest.approx(float(expected.iloc[-1]))
+    assert brick_chart.points[0].trade_date == history.bars[10].trade_date
+    assert brick_chart.points[0].brick_chart == pytest.approx(float(expected.iloc[10]))
+
+
 def test_chart_rejects_empty_history() -> None:
     reader = FakeReader(StockHistory(ts_code="000001.SZ", name="平安银行"))