Fix option close reduceOnly flag and use position mark when quote has no bid.

OKX expects reduceOnly as the string true; target auto-close also falls back to the live position mark price on empty books.

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

lib/exchange/okx_options_lib.py

@@ -793,7 +793,7 @@ def place_option_limit_order(
     if pos_side:
         body["posSide"] = pos_side
     if reduce_only:
-        body["reduceOnly"] = True
+        body["reduceOnly"] = "true"
     try:
         resp = ex.private_post_trade_order(body)
         data = (resp or {}).get("data") or []
@@ -829,7 +829,7 @@ def place_option_market_order(
     if pos_side:
         body["posSide"] = pos_side
     if reduce_only:
-        body["reduceOnly"] = True
+        body["reduceOnly"] = "true"
     try:
         resp = ex.private_post_trade_order(body)
         data = (resp or {}).get("data") or []