fix: anchor hedge contribution bars at zero

tests/test_hedge_metrics.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from app.pages.common import strategy_metrics
+from app.pages.hedge import _waterfall_options
 
 
 def test_protective_put_atm_minus_20pct_improves_equity() -> None:
@@ -18,3 +19,13 @@ def test_protective_put_atm_minus_20pct_improves_equity() -> None:
         ("Hedge cost", -6_250.0),
         ("Net equity", 58_750.0),
     ]
+
+
+def test_hedge_waterfall_uses_zero_based_contribution_bars() -> None:
+    options = _waterfall_options(strategy_metrics("protective_put_atm", -20))
+
+    assert len(options["series"]) == 1
+    assert options["series"][0]["type"] == "bar"
+    values = options["series"][0]["data"]
+    assert values[2]["value"] == 38_000.0
+    assert values[2]["itemStyle"]["color"] == "#22c55e"