v4.0.0

Changes

• Breaking: Replace the long-dormant rest-client transport with Faraday 2 and faraday-multipart.
• Breaking: Raise the minimum supported Ruby version from 3.0 to 3.1.
• Keep HTTP client types out of SDK responses and exceptions while preserving response status, headers, body access, multipart ordering, and rate-limit retries.
• Add a v3 to v4 migration guide.
• Test all Ruby versions from the supported minimum through Ruby 4.0.