Migrate image generation from DALL‑E to gpt-image-1-mini

[Copilot]

DALL‑E deprecation requires moving image generation to gpt-image-1-mini and updating the OpenAI SDK usage accordingly. This change updates the library to the latest OpenAI client and adapts outputs to GPT image model responses.

• API migration
  • Switch image model defaults/types to gpt-image-1-mini
  • Generate PNG base64 data URLs from GPT image responses
• Docs & examples
  • Update README and E2E example usage to reflect the new model and data URL outputs

Example:

const imageUrl = await imageGen.generateImage(
  "A sunset over mountains",
  "1024x1024",
  "gpt-image-1-mini"
);
// imageUrl is a PNG data URL

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• developers.openai.com
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)