Function verify_display_field 

pub fn verify_display_field(
    field_name: &str,
    actual: &str,
    supplied: &str,
    rerun_tool: &str,
) -> ChatbotResult<()>

Re-verifies a model-supplied display field against actual, per ConfirmableActionTool::execute’s contract: refuses with a descriptive error naming field_name and rerun_tool instead of mutating on a mismatch.