Plan 3 of the web embedding SDK: @zseven-w/op-web-sdk-react and -vue — thin
read-only framework adapters over the TS core. Each: <DesignView> (canvas +
viewer lifecycle), provider/inject of OpViewer, and read-only
useDocument/useViewport/useActivePage. React via useSyncExternalStore
(cache-invalidate-on-event); Vue via an async shallowRef provider so children
inject the viewer after load. Self-contained (no pen-* deps; framework peer);
React 5/5 + Vue 4/4 tests; both tsc clean.
