[breaking] OpenAI deprecates the GPT Image 1 family, shutdown December 2026

gpt-image-1-mini, gpt-image-1.5, and chatgpt-image-latest were deprecated June 2, 2026 and shut down December 1, 2026. Recommended replacement: gpt-image-2. Effective: 2026-12-01. Migration target: openai/gpt-image-2. Affected: openai/gpt-image-1-mini, openai/gpt-image-1.5, openai/chatgpt-image-latest. Severity: breaking. Verification: verified.