Cap options budget-full sizing at min(balance, trade budget) with UI hint.

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

lib/options/options_pricing_lib.py

@@ -259,6 +259,11 @@ def eth_amount_from_sheets(sheets: int, ct_mult: float = 0.01) -> float:
     return round(int(sheets) * float(ct_mult), 8)
 
 
+def resolve_budget_full_usdc(trading_usdc: float, trade_budget_usdc: float) -> float:
+    """按可用余额打满:余额大于预算用预算,否则用余额."""
+    return min(float(trading_usdc), float(trade_budget_usdc))
+
+
 def calc_order_size(
     *,
     quote_per_unit: float,