test: measure live page readiness in page

[jackhai9]

Summary

• prepare and resolve live completion inside the Binance page before external control actions
• preserve performance-observer tail evidence without adding browser-control latency
• refresh the isolated no-order live baseline from three validated CDP samples

Validation

• npm run test:binance-orderbook-ui-toolchain
• npm run test:ui
• npm test
• npm run build:binance-orderbook-trade
• npm run check:binance-orderbook-trade
• npm run summarize:binance-orderbook-live -- e2e/binance-orderbook/live-baselines/no-orders-2026-08-27-page-ready.capture.json --compare e2e/binance-orderbook/live-baselines/no-orders.baseline.json --enforce
• git diff --check