Implement P1 local matcher/ledger and P2 strategy engine.

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

backend/app/sim/liquidity.py

@@ -0,0 +1,19 @@
+"""期权买一流动性：张数 × ctMult 是否覆盖名义 ETH。"""
+
+from __future__ import annotations
+
+
+def contracts_for_eth(qty_eth: float, ct_mult: float) -> float:
+    m = float(ct_mult) if ct_mult and ct_mult > 0 else 0.01
+    return float(qty_eth) / m
+
+
+def eth_from_contracts(contracts: float, ct_mult: float) -> float:
+    m = float(ct_mult) if ct_mult and ct_mult > 0 else 0.01
+    return float(contracts) * m
+
+
+def bid_covers_eth(*, bid_sz_contracts: float | None, ct_mult: float, need_eth: float) -> bool:
+    if bid_sz_contracts is None or bid_sz_contracts <= 0:
+        return False
+    return eth_from_contracts(bid_sz_contracts, ct_mult) + 1e-12 >= float(need_eth)