Keep chart order lines visible during bulk cancel

[jackhai9]

Summary

• keep Binance chart order lines visible throughout native bulk cancellation
• coalesce only removal-triggered chart saves after confirmation
• preserve synchronous unrelated saves and drop stale snapshots when save ownership changes

Validation

• npm test (520 passed)
• npm run build:binance-orderbook-trade
• npm run check:binance-orderbook-trade
• npx playwright test e2e/binance-orderbook/specs/cancel-covering-matrix.pw.js e2e/binance-orderbook/specs/cancel-current-symbol.pw.js (38 passed)
• git diff --check