Bindings between boa-cat (JS engine) and the DOM (html-cat tree) plus fetch (net-cat). Exposes `document`, `Element` methods, and `fetch` as boa-cat NativeFns so scripts can read/mutate a parsed HTML document and make synchronous HTTP requests. v0.2.0 adds `extract_document` that walks the post-script JS-side DOM tree and reconstructs a `dom_cat::Document` so callers can back-propagate scripted mutations into layout-cat. No mut, no Rc/Arc, no interior mutability, no panics. Seventh sub-crate of a Servo-replacement webview runtime targeting Tauri.