feat(v3.6.6): sync margin OTO lists, loan LTV, FX schedule, and futures symbol type, update package version to 3.6.6

[JJ-Cro]

Summary

• USD-M trading schedule: FX market (REGULAR / NO_TRADING)
• Institutional loan GET /sapi/v1/margin/loan-group/ltv-details: leverage tier, LTV thresholds, transferOutLtv, frozen amount, max transfer-out, and max borrow limit
• Margin GET /sapi/v1/margin/oto/openOrderList for open OTO / OTOCO lists
• Margin OTOCO response contingencyType is OTO | OTOCO. User-data listStatus accepts OCO, OTO, OTOCO, OPO, and OPOCO
• Margin order fills: commission and commissionAsset can be null
• Margin UTA listen keys: POST / PUT / DELETE /sapi/v2/margin/uta/listen-key, plus marginLevelChange and liabilityChange events
• Algo cancel on spot and futures accepts algoId or clientAlgoId
• Sub-account futures move-position supports OPTION. positionSide is optional and can come back null. History query takes optional productType
• Merged USD-M / COIN-M market streams: optional symbolType (1 = USD-M, 2 = COIN-M) on aggTrade, tickers, book ticker, depth, mark price, force order, and contract info
• Version: 3.6.5 → 3.6.6
• Build / lint / regex: npm run build, npm run lint, and npm run binance passed

The websocket client still opens the existing margin listen key URL. It does not yet connect to wss://fstream.binance.com/private/ws/<listenKey>. Stocks trading (/sapi/v1/equity/*) is not in this release.

[tiagosiebler]

lgtm