Use gpt-image-2.5-flare as our default OpenAI image generation model

[dkotter]

What?

Sets the new gpt-image-2.5-flare model as the default when generating images using OpenAI

Why?

OpenAI recently released two new image generation models, gpt-image-2.5-flare and gpt-image-2.5-sunburst. They recommend using gpt-image-2.5-flare as the model for most use cases so this PR bumps that as our default. Users can still set their own desired model if needed.

How?

Set gpt-image-2.5-flare as the default OpenAI image generation model with gpt-image-2 now the second fallback

Use of AI Tools

No

Testing Instructions

1. Ensure you have OpenAI configured and the Image Generation feature turned on
2. Generate an image and ensure that still works

Changelog Entry

Changed - Use gpt-image-2.5-flare as our default OpenAI image generation model.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: dkotter <dkotter@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.51%. Comparing base (f5dd5d8) to head (112ac76).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #1023   +/-   ##
==========================================
  Coverage      81.51%   81.51%           
  Complexity      2924     2924           
==========================================
  Files            122      122           
  Lines          11655    11655           
==========================================
  Hits            9500     9500           
  Misses          2155     2155           

Flag	Coverage Δ
unit	81.51% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.