ECMAScript runtime: native built-ins (console, Math, JSON, parseInt, isNaN, Promise, ...) that the boa-cat engine exposes to scripts. v0.3.0 adds the `Promise` global with `resolve(v)`, `reject(v)`, `all(arr)`, and `race(arr)` static methods, wrapping the boa-cat 0.6 promise infrastructure (`Heap::alloc_promise`, microtask driver, `.then` / `.catch` dispatch). `Promise.resolve(p)` short-circuits for existing promises per spec; `all` / `race` over fully-settled inputs work synchronously, and the Pending-input orchestration lands once boa-cat ships continuation-passing transforms.