Replace AXS card with OPENAI and add OKX source support for perp tickers

[amazing-fish]

Motivation

• Replace the AXS perpetual card with an OPENAI perpetual card per review and standardize multi-exchange ticker handling.
• Introduce OKX as a new data source and map its fields to the unified price/change/percent/ts rendering contract.
• Bump the userscript version to reflect the feature change and document the update in project anchors and audit log.

Description

• Add @connect www.okx.com and update the userscript header version to v1.7.0 in AlphaBoard.js.
• Replace the AXS entry in FEATURE_CARDS with an OPENAI-USDT-SWAP card sourced from OKX and update BTC/XAU cards to call the unified fetch wrapper via fetchPerpTicker({ source, symbol }).
• Change fetchPerpTicker to accept an object { source, symbol }, add OKX parsing logic that maps last/open24h/sodUtc0 to the unified price/change/percent/ts output, and keep Binance parsing for fapi/v1/ticker/24hr.
• Remove the old specialized fetchBtcPerpTicker, fetchXauPerpTicker, and fetchAxsPerpTicker helpers and update ANCHOR.md and docs/audit.log to reflect the feature changes.

Testing

• Ran node --check AlphaBoard.js syntax checks after the changes and they passed.
• Confirmed updated audit entries and ANCHOR.md reflect the v1.7.0 feature additions and the OKX/OPENAI card replacement with successful node --check AlphaBoard.js validation.

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Codex Task