feat: clear-sign x402 payments

[BitHighlander]

Purpose

Stage hdwallet transport support for hardware-verifiable x402 payments on the existing ClearSign/Ironwood integration branch. No package is published by this PR.

Changes

• route the official default EVM x402 EIP-3009 TransferWithAuthorization shape through firmware's structured EIP-712 endpoint
• synthesize the standard EIP712Domain type when the x402 client omits it, matching EIP-712 V4 behavior
• serialize bigint values losslessly as decimal strings
• keep all non-EIP-3009 typed data on the existing path; firmware continues to gate precomputed typed hashes behind AdvancedMode
• expose Solana token metadata and recipient-owner candidates in hdwallet-core
• append canonical protobuf fields 4 and 12 without publishing generated protocol bindings
• validate Solana public keys and token metadata before transport

Validation

• focused Jest suites: 3 suites, 10 tests passed
• hdwallet-core TypeScript compile: passed
• hdwallet-keepkey TypeScript compile: passed
• full yarn build: passed
• full candidate-firmware Python integration: 585 passed, 12 skipped, 0 failed
• EVM and Solana x402 device tests pass with AdvancedMode disabled

SOP

This PR targets feat/clearsign-studio-ironwood, the canonical hdwallet staging branch consumed by Vault. It does not publish npm, merge to master, cut firmware RC23, or release anything. Once reviewed and merged, Vault will pin the exact staging merge SHA.

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Project	Deployment	Actions	Updated (UTC)
hdwallet-sandbox	Ready	Preview	Jul 31, 2026 8:41pm