feat: accept starknet address when fetching vp or validation

[wa0x6e]

Toward https://github.com/snapshot-labs/workflow/issues/562

This PR allows starknet addresses when calling get_vp, validate and getScores

[Copilot]

Pull Request Overview

This PR extends address validation to include Starknet addresses in utility functions.

• Updated isValidAddress to accept Starknet addresses via isStarknetAddress.
• Ensured empty-address exclusion remains in place.

Comments suppressed due to low confidence (2)

src/utils.ts:796

• Update the JSDoc or comments for isValidAddress to indicate that it now also supports Starknet addresses.

function isValidAddress(address: string) {

src/utils.ts:798

• Add unit tests to cover the new Starknet address validation path in isValidAddress to ensure correct behavior.

(isAddress(address) || isStarknetAddress(address)) &&

[bonustrack]

utACK