feat(tempo): support machine-token charge payments

[gakonst]

Summary

• add canonical machineUSD deployments and exact approve + swapTo routing for Tempo mainnet and Moderato
• prefer funded, successfully simulated machine-token routes before autoswap on charge clients
• advertise machineTokenEnabled from server builders and verify canonical calls and swapper settlement logs

Ports the behavior merged in wevm/mppx#784.

Verification

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo test --features tempo,stripe,ws,server,client,axum,middleware,tower,utils,integration-stripe,integration-ws
• cargo test --all-features --lib machine_token

The external Tempo localnet suite was not run because localhost:8545 was not running.

[github-actions]

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Preview

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mpp: minor
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Added canonical first-party machine-token funding for Tempo charges. Clients now prefer the machineUSD approve/`swapTo` route when `machineTokenEnabled` is set and the payer is funded, and verification accepts the canonical swapper as the settlement sender.

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