Bindings between boa-cat (JS engine) and the DOM (html-cat tree) plus fetch (net-cat). v0.7.1 upgrades `fetch(url)` to return a `Promise<Response>` matching the DOM Fetch API shape: success becomes a resolved Promise carrying the response Object; bad URL / argument errors become a rejected Promise with a `TypeError:`-prefixed string reason; `response.text()` returns a resolved `Promise<string>` of the body; `response.json()` is a rejected-stub deferring to `JSON.parse(await r.text())` (ecma-runtime-cat already exposes JSON.parse). Scripts now use `await fetch(url)` and `fetch(url).then(r => r.text())` end-to-end through the engine's microtask driver. Seventh sub-crate of a Servo-replacement webview runtime targeting Tauri.