Sync SDK docs with contracts v3 API

[mintlify]

Summary

• Updated 21 SDK documentation pages to reflect contracts v3 breaking changes
• Removed nonce parameter from all RefundRequest functions (one request per payment, keyed by paymentInfoHash)
• Replaced approveRefundRequest() with auto-approval via refundInEscrow() (RefundRequest is now an IRecorder plugin)
• Updated all code examples from class constructors to factory functions (createPayerClient, createMerchantClient, createArbiterClient)
• Replaced getNetworkConfig with getChainConfig across all pages
• Added Linea (59144) and SKALE Base (1187947933) to network support tables
• Updated deploy-operator architecture: refundInEscrowCondition now uses ReceiverCondition, added refundInEscrowRecorder slot
• Updated action group API pattern (client.refund.request() instead of client.requestRefund())
• Replaced compositeKey with paymentInfoHash in getRefundRequestByKey