Bindings between boa-cat (JS engine) and the DOM (html-cat tree) plus fetch (net-cat). v0.5.0 bumps to boa-cat 0.6 + ecma-parse-cat 0.2 to track the async stack across the workspace: existing match arms gain `Value::Promise(_) => None` so DOM extraction skips engine-allocated promises, and the v0.4 `document.cookie` accessor pair continues to work unchanged on top of the new engine surface. Seventh sub-crate of a Servo-replacement webview runtime targeting Tauri.