feat: allow builder-authenticated clients to query orders

[suhailkakar]

Note

Medium Risk
Changes request authentication headers for order-query endpoints; incorrect header selection or builder signing failures could cause auth errors or unexpected access behavior.

Overview
Builder-authenticated clients can now query orders. ClobClient.getOrder() and ClobClient.getOpenOrders() attempt to generate and inject builder headers (via existing builder config) and fall back to standard L2 headers when builder auth isn’t available.

Adds examples/getBuilderOpenOrders.ts, a runnable script showing how to configure BuilderConfig (local creds or remote signer) and call getOpenOrders() using env-based credentials.

^{Written by Cursor Bugbot for commit d69e93a. This will update automatically on new commits. Configure here.}