Align hedge-plan perp contract precision with exchange and show TP/SL USDT PnL.

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

tests/test_hedge_plan_calc.py

@@ -4,6 +4,7 @@ import unittest
 from lib.hedge_plan.hedge_plan_calc_lib import (
     build_options_options_preview,
     build_perp_options_preview,
+    floor_contracts_to_precision,
     gate_status,
     option_expiry_pnl,
     option_premium_total,
@@ -81,6 +82,11 @@ class TestHedgePlanCalc(unittest.TestCase):
             10,
         )
 
+    def test_floor_contracts_to_precision(self):
+        self.assertEqual(floor_contracts_to_precision(4.569713, 4), 4.5697)
+        self.assertEqual(floor_contracts_to_precision(4.569713, 0), 4.0)
+        self.assertEqual(floor_contracts_to_precision(0, 4), 0.0)
+
 
 if __name__ == "__main__":
     unittest.main()