ECMAScript runtime: native built-ins (console, Math, JSON, parseInt, isNaN, Promise, Object, Array, ...) that the boa-cat engine exposes to scripts. v0.3.3 adds `Object.{keys, values, entries, assign}` and `Array.isArray` static methods. All four `Object` methods walk own data properties and skip the synthetic `length` slot when the source looks like an array; `Object.assign` also copies accessor pairs onto the target so getter/setter semantics survive the merge. `Array.isArray(value)` returns `true` when `value` is an object whose own data-property keys are numeric or `length`.