Function evaluate_operator_config 

pub fn evaluate_operator_config(
    expressions: &[Expression],
    routines: &Routines,
    runtime_context: &RuntimeContext,
) -> Result<BTreeMap<String, Value>>

Evaluate a list of expressions into operator configuration

Only processes Expression::Alias variants:

• The alias name becomes the BTreeMap key
• The inner expression is evaluated to become the value
• Non-Alias expressions are skipped