feat(sdk): add EthereumService with viem contract instances for all Audius ETH contracts

[rickyrombo]

Summary

• Introduces EthereumService — a new SDK service exposing viem contract instances for all 10 Audius Ethereum contracts (AudiusToken, AudiusWormhole, Staking, DelegateManager, Governance, ServiceProviderFactory, ClaimsManager, EthRewardsManager, ServiceTypeManager, TrustedNotifierManager)
• Follows SDK service patterns — uses getDefaultEthereumServiceConfig + mergeConfigWithDefaults for config, with per-environment address overrides
• Moves Ethereum clients into the service — publicClient, ethWalletClient, and audiusWalletClient are constructor params on EthereumService; no longer separate fields on ServicesContainer
• Removes standalone helpers — callers use sdk.services.ethereum.<contract>.read.* directly instead of one-off helper functions
• Removes @audius/common ethereum wrapper — deleted packages/common/src/services/ethereum/ethereum.ts; AudiusBackend.ts and useAudioBalance.ts now use sdk.services.ethereum contracts directly
• Restores identity-relay ethWalletClient for web — web's audiusSdk.ts injects a custom EthereumService with a viem wallet client that proxies writes through IDENTITY_SERVICE/ethereum/rpc so identity pays gas fees

Key design decisions

• Dual-client getContract({ client: { public, wallet } }) gives every contract instance both .read.* and .simulate.* (and .write.*) without needing to thread clients through every call site
• Explicit GetContractReturnType<Abi, { public: PublicClient; wallet: WalletClient }> annotations on contract properties — avoids TypeScript "type too large to serialize" errors from inference
• audiusWalletClient stored privately on EthereumService; permitAudioToken and wormholeTransferTokens use it directly for typed-data signing with no extra parameters

Test plan

• Web typechecks pass (npm run typecheck in packages/web)
• Common typechecks pass (npm run typecheck in packages/common)
• SDK typechecks pass (npm run typecheck in packages/sdk)
• ETH→SOL AUDIO transfer flow works (permit + Wormhole bridge) in web app
• Wallet balance display works in web app (reads from audiusToken.read.balanceOf, staking.read.totalStakedFor, delegateManager.read.getTotalDelegatorStake)

🤖 Generated with Claude Code

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[changeset-bot]

🦋 Changeset detected

Latest commit: 7794bbd

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@audius/sdk	Major
@audius/sdk-legacy	Patch
@audius/sp-actions	Patch

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[github-actions]

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