Add WalletClient support to ExchangeOrderBuilder

[carlos-poly]

Summary

This PR adds viem WalletClient support to ExchangeOrderBuilder while preserving compatibility with existing ethers signers (Wallet | JsonRpcSigner).

What changed

• Refactored signer handling in ExchangeOrderBuilder to use a local minimal signer abstraction.
• Expanded constructor signer input to:
  • Wallet | JsonRpcSigner | WalletClient
• Replaced direct signer calls with adapter behavior:
  • Address resolution: account.address for WalletClient
  • Typed data signing: walletClient.signTypedData(...) for WalletClient
• Preserved existing ethers behavior:
  • getAddress()
  • _signTypedData(...)
• Added fail-fast validation for viem clients without a hoisted account:
  • throws walletClient.account is required
• Added WalletClient tests:
  • successful order build using account.address
  • deterministic typed-data signature path
  • missing-account error path
• Bumped package version in package.json:
  • 3.1.0 → 3.2.0

Why

Consumers can now use viem wallet clients directly without wrapping them in ethers-compatible signers.

Backward compatibility

• No breaking API change to constructor shape/order.
• Existing ethers-based integrations continue to work unchanged.

Validation

• pnpm test passes
• pnpm build passes

---

Note

Medium Risk
Touches order signing/address validation logic; while behavior is intended to be backwards-compatible, adapter detection and typed-data signing differences could break integrations if signer objects don’t match expected shapes.

Overview
Adds viem WalletClient support to ExchangeOrderBuilder. The constructor now accepts Wallet | JsonRpcSigner | WalletClient and routes address resolution and EIP-712 signing through a minimal IExchangeSigner adapter (including a fail-fast error when walletClient.account is missing).

Updates tests and release version. Adds a new test suite covering WalletClient order building, deterministic typed-data signatures, and the missing-account error case, and bumps package.json from 3.1.0 to 3.2.0.

^{Written by Cursor Bugbot for commit 136452e. This will update automatically on new commits. Configure here.}

[carlos-poly]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add WalletClient support to ExchangeOrderBuilder #20 👈 (View in Graphite)
• Switch to pnpm and Node.js 24 #19
• main

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[carlos-poly]

Tackled in Polymarket/clob-client#313