[breaking] Azure AI Foundry retires gpt-4o, gpt-4o-mini on 2026-10-01

Azure AI Foundry lists gpt-4o (2024-05-13), gpt-4o (2024-08-06), gpt-4o (2024-11-20), gpt-4o-mini (2024-07-18) as deprecated with retirement on 2026-10-01; suggested replacements: gpt-5.1, gpt-4.1-mini. Azure retirement dates are platform-specific and may differ from the model provider's own schedule. The page does not date the announcements; announced_at reflects the page capture date. Effective: 2026-10-01. Affected: microsoft/gpt-4o-2024-05-13, microsoft/gpt-4o-2024-08-06, microsoft/gpt-4o-2024-11-20, microsoft/gpt-4o-mini-2024-07-18. Severity: breaking. Verification: verified.