fix: hold a WebSocket close behind delayed frames, batch reports, hide wrapper internals

[vannt-dev]

Three of the minor follow-ups listed in #20.

• Close order. When a socket closed while received frames were still delayed, the page got close first and the frames were dropped. The close event is now held until those frames are delivered, then re-dispatched with the same code, reason and wasClean. Like the frames, the re-dispatched event has isTrusted === false, and readyState is already CLOSED while the last frames arrive. Frames waiting to be sent are still dropped: the socket is gone.
• Reports. The wrapper sent one binding call per changed frame. It now counts and sends one report per 250 ms; the background adds the count, bounded to 1–1000 per report since the page can call the binding itself. A page that unloads within that window loses those counts (statistics only).
• Page-visible internals. The per-socket queue and the "re-dispatched" mark were properties on the socket and the event; they are now a WeakMap/WeakSet. window.__networkOverridesWsWrapper stays (the background needs it to clear rules) but is no longer enumerable.

Not done, on purpose:

• attaching waits while an alert() is open — Runtime.evaluate cannot run under a dialog; nothing short of dismissing the page's dialog fixes it;
• rules for the old origin applying briefly after a cross-origin navigation, and the small modal leftovers — no concrete defect to fix yet.

Tests

npm test 186/186 (5 new), npm run lint clean, npm run smoke 16/16, node scripts/e2e-websocket.mjs OK on Chromium.

🤖 Generated with Claude Code