When using OpenAI provider, getPublicModelDisplayName() was incorrectly
returning "Opus 4.6" because CLAUDE_OPUS_4_6_CONFIG.openai maps to 'gpt-4o',
causing a false match in the switch statement. Now returns null for OpenAI
provider so the raw model name (e.g. 'gpt-4o') is displayed directly.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>