fix: skip auth and onboarding for OpenAI provider in interactive mode

The interactive REPL was hanging because isAnthropicAuthEnabled() didn't
recognize CLAUDE_CODE_USE_OPENAI as a 3rd party provider, triggering
OAuth flows. Also skip setup screens (onboarding, trust dialog) when
using the OpenAI shim.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/interactiveHelpers.tsx

@@ -103,6 +103,7 @@ export async function renderAndRun(root: Root, element: React.ReactNode): Promis
 }
 export async function showSetupScreens(root: Root, permissionMode: PermissionMode, allowDangerouslySkipPermissions: boolean, commands?: Command[], claudeInChrome?: boolean, devChannels?: ChannelEntry[]): Promise<boolean> {
   if ("production" === 'test' || isEnvTruthy(false) || process.env.IS_DEMO // Skip onboarding in demo mode
+  || isEnvTruthy(process.env.CLAUDE_CODE_USE_OPENAI) // Skip onboarding for OpenAI provider
   ) {
     return false;
   }