[Docs][Accessibility]: v4 docs OAuth diagram poor visibility

What is the improvement or update you wish to see?

The v4 docs page on OAuth providers renders a diagram of an OAuth workflow with poor color contrast in dark mode. Update the colors of the affected text to meet minimum AA standards for accessible text.

Is there any context that might help us understand?

The v4 docs page renders a SVG diagram of an OAuth workflow. The SVG text elements do not update their color to suit the users selected theme (dark mode/light mode). Instead these elements render text with color #333 on a black background, resulting in a color contrast ratio of 1.66:1. The minimum ratio for color contrast for text is 4.5:1 with some exceptions (See WCAG Success Criterio 1.4.3). Observed 10/21/25 via Google Chrome Version 140.0.7339.133

Does the docs page already exist? Please link to it.

https://next-auth.js.org/configuration/providers/oauth

Open the v4 OAuth providers page at the linked URL and inspect its OAuth workflow SVG in dark mode. Identify the affected text elements and update their colors so text meets the stated WCAG AA contrast requirement, then verify the diagram in both dark and light themes.