Function evaluate_constant_value 

pub fn evaluate_constant_value(
    name: &str,
    contract: &Contract,
    span: &AstSpan,
) -> Result<usize, CodegenError>

Evaluates a constant to its numeric value as a usize

This is useful for builtin functions that need numeric constant values (e.g., __ASSERT_PC) without generating bytecode.

Returns an error if:

• The constant doesn’t exist
• The constant is __NOOP (has no numeric value)
• The constant is a builtin function call
• The constant value exceeds usize::MAX