Add hub strategy calculator page with trend and roll risk-based sizing.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_hub_calculator_lib.py

@@ -0,0 +1,60 @@
+"""hub_calculator_lib 测算逻辑。"""
+
+from hub_calculator_lib import calc_roll_calculator, calc_trend_calculator
+
+
+def test_trend_calculator_long_basic():
+    data, err = calc_trend_calculator(
+        direction="long",
+        capital_usdt=1000,
+        risk_percent=5,
+        leverage=5,
+        entry_price=100,
+        stop_loss=95,
+        add_upper=110,
+        take_profit=120,
+        dca_legs=3,
+        contract_size=1,
+    )
+    assert err is None
+    assert data is not None
+    assert data["risk_budget_u"] == 50.0
+    assert len(data["rows"]) >= 2
+    assert data["rows"][0]["label"] == "首仓"
+    assert data["first_profit_u"] is not None
+    assert data["first_profit_u"] > 0
+
+
+def test_trend_calculator_short_rejects_bad_bounds():
+    data, err = calc_trend_calculator(
+        direction="short",
+        capital_usdt=1000,
+        risk_percent=5,
+        leverage=5,
+        entry_price=100,
+        stop_loss=90,
+        add_upper=110,
+        take_profit=80,
+        dca_legs=3,
+    )
+    assert data is None
+    assert err is not None
+
+
+def test_roll_calculator_long():
+    data, err = calc_roll_calculator(
+        direction="long",
+        capital_usdt=1000,
+        risk_percent=5,
+        qty_existing=10,
+        entry_existing=100,
+        take_profit=120,
+        add_price=105,
+        new_stop_loss=98,
+        legs_done=0,
+    )
+    assert err is None
+    assert data is not None
+    assert data["add_contracts"] > 0
+    assert data["qty_after"] > 10
+    assert data["profit_at_tp_u"] is not None