PARENT_BOUND_HELPERS: ReadonlySet<string> = ...

Helper names that receive the evaluating SafeExpression's owning parent Logic as an injected first argument. SafeExpression prepends this.parent for these before calling the helper, so an expression author still calls them with only their documented arguments (e.g. roll(formula)).

Used by helpers that must construct a parent-owned domain object (a SimpleRoll needs an owning Logic). Kept here, beside the helpers, so the registry declares which of its helpers need the parent and SafeExpression merely honors it.