Remove/migrate deprecated OpenAI models — October 23, 2026 shutdown

[ocs-percy]

Action issue to remove or migrate any usage of OpenAI models shutting down on October 23, 2026.

Deprecation tracking: #3208

Models being shut down

• gpt-3.5-turbo-0125
• gpt-4-0613
• gpt-4-1106-preview
• gpt-4-turbo
• gpt-4.1-nano
• gpt-4o-2024-05-13
• gpt-image-1
• o1-2024-12-17
• o1-pro-2025-03-19
• o3-mini-2025-01-31
• o4-mini-2025-04-16

Tasks

• Search codebase for hardcoded references to the above model names
• Update any default/fallback model configs that reference these models
• Update test fixtures or mocks referencing these model names
• Verify no user-facing model dropdowns expose deprecated options without a migration path
• Merged before October 16, 2026