Fix RPI depth snapshot bridging

[jackhai9]

Summary

• accept the first RPI depth event when its pu exactly names the observed snapshot update ID
• preserve standard U..u snapshot coverage and strict pu === previous.u checks for later non-stale events
• reject descending update ID ranges before mutating book state
• bump the orderbook userscript to 2.7.213 and rebuild the install artifact

Testing

• npm test — 2087 passed on Node.js 24.16.0
• npm run test:ui — 372 passed on Node.js 24.16.0
• npm run lint:tests
• npm run test:binance-orderbook-trade — 855 passed
• npm run build:binance-orderbook-trade
• npm run check:binance-orderbook-trade
• npm run inspect:binance-orderbook-trade
• git diff --check

An initial Playwright run used Node.js 26.8.2 and the seven coverage-merge cases were rejected by the repositories explicit Node.js 24.16.0 version guard. The complete suite then passed under the pinned runtime.