Function preprocess_script 

pub fn preprocess_script(script: &str) -> String

Replace cell references like “A1” with Rhai function calls like “cell(0, 0)”. Typed refs like “@A1” become “value(0, 0)” (returns Dynamic). Also transforms range functions like SUM(A1:B5, …) into sum_range(0, 0, 4, 1, …).