Model, API, and feature updates

• The GPT-4.1 family includes gpt-4.1, gpt-4.1-mini, and gpt-4.1-nano.
• GPT-4.1 has a 1M-token context window and low latency without a reasoning step.
• The family supports the Responses API and Chat Completions API.
• GPT-4.1 and GPT-4.1 mini support supervised fine-tuning.
• Supported tools include function calling, web search, file search, image generation, code interpreter, and remote MCP.