feat(tempo): settle machineUSD sessions atomically

[decofe]

Summary

• bind machineUSD session settlement routes into TIP-1034 descriptor salts
• persist and validate adapter, logical recipient, target token, and route salt across channel reuse
• settle, convert, and close fully consumed sessions atomically; reject refunding machineUSD closes

Validation

• env -u HOSTNAME cargo test --all-features --lib --quiet
• cargo test --all-features --doc --quiet
• cargo +nightly fmt --all -- --check
• cargo +nightly clippy --all-targets --all-features -- -D warnings
• Full integration suite requires the repository local node on localhost:8545; without it, integration_charge fails to connect.

Prompted by: @gakonst

[github-actions]

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