Playground OAuth discovery fix and error handling for MCP tool results

This release fixes OAuth discovery in the playground to use toolset-level configuration and sets error status on MCP tool results based on HTTP response codes.

Features

• Display audience field in OAuth proxy server details #1862 - The OAuth proxy server details view now displays the audience field. (Author: @simplesagar)
• Set isError on MCP tool results based on HTTP status #1887 - MCP tool results now have isError set based on the HTTP response status code, improving error visibility for tool calls. (Author: @minuteman3)

Bug fixes

• Fix playground OAuth discovery #1861 - Resolved an issue where the playground OAuth discovery relied on removed tool-definition fields. OAuth requirements are now detected from toolset.oauthProxyServer and toolset.externalOauthServer at the toolset level. (Author: @simplesagar)