Function vertical_open_position_context 

pub fn vertical_open_position_context(
    chain: &Value,
    underlying: &str,
    _today: NaiveDate,
    expiry: NaiveDate,
    strike_map: &Value,
    short_strike: f64,
    long_strike: f64,
    is_put_spread: bool,
    entry_credit: Option<f64>,
    debit_to_close: Option<f64>,
    profit_pct: Option<f64>,
    dte: i64,
    contracts: u32,
) -> Value

Live chain context for an open vertical spread (monitor / LLM phase).