feat: add optional derivationPath for Ethereum HD wallets

[jfrank-summit]

Summary

• Introduces an optional derivationPath parameter to wallet setup/activation for intuitive Ethereum HD derivation without changing defaults.
• Updates example with a runnable demo and ethers parity checks.
• Adds tests that lock in the expected Ethereum BIP44 address for a known mnemonic.

Motivation and context

• Address mismatch with standard Ethereum wallets (e.g., MetaMask) occurs because current behavior derives at master (m) unless a path is provided.
• Per issue Ethereum Wallet Derivation Path Does Not Follow BIP44 Standard #482, we provide a clearer, explicit way to opt into BIP44 without breaking existing behavior.

Close #482

[jfrank-summit]

bugbot run

[cursor]

✅ Bugbot reviewed your changes and found no bugs!

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[jim-counter]

LGTM!