[breaking] Azure AI Foundry retires o4-mini on 2026-10-16

Azure AI Foundry lists o4-mini (2025-04-16) as deprecated with retirement on 2026-10-16. 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: 2026-10-16. Affected: microsoft/o4-mini-2025-04-16. Severity: breaking. Verification: verified.