test: verify x402 payments on Solana and EVM

[BitHighlander]

Purpose

Stage the protocol binding, client plumbing, and release evidence for hardware-verifiable x402 payments without publishing a package or merging a release branch.

Changes

• pin device-protocol exactly to merged staging SHA 5a8e2702a4cc5f6e6c401f9cbb9bb07b43828c8b
• regenerate messages_solana_pb2.py with repository-standard protoc 3.5.1
• add optional Solana token info and verified recipient-owner candidates
• add a high-level structured EIP-712 client path; precomputed typed-hash signing remains AdvancedMode-only
• add the official default EVM x402 EIP-3009 TransferWithAuthorization fixture
• add the standard sponsored, zero-LUT Solana v0 USDC TransferChecked + Memo fixture
• add both x402 cases to the generated firmware test PDF
• assert protobuf field 12 serialization on modern protobuf runtimes

Firmware treats recipient owners as untrusted candidates and displays one only after independently deriving its ATA and matching the signed destination.

Validation against the candidate firmware

• full Python integration: 585 passed, 12 skipped, 0 failed
• screenshot suite: 188 passed, 0 failed
• x402 EVM and Solana tests pass with AdvancedMode disabled
• generated PDF: 308 selected tests, 304 passed, 3 pre-existing skips, 1 disclosed pre-existing pending, 0 failures
• EVM reference domain and message hashes match independent EIP-712 V4 values
• Solana screenshots show known mainnet USDC, verified recipient owner, and 0.002 USDC

SOP

This PR targets the canonical reconcile/upstream-sync staging branch. It does not publish Python/device-protocol packages, merge firmware upstream, cut an RC, or release anything. The merged staging SHA will become the exact firmware submodule pin before the fork firmware PR is opened.