[Bug]: Sidebar item hover background colour makes text unreadable

[NickyBlissTui]

Describe the bug

The sidebar item hover background colour variable "--tree-node-background-hover" is being updated on hover and focus to a lighter or darker shade of the themes secondary colour but the font colour is not being updated to accommodate this change mean that now the text is unreadable when the items are in hover or focus.

Reproduction link

https://stackblitz.com/edit/github-djnsqscp?file=package.json

Reproduction steps

1. Update from 8.4.7 to 8.5.0+
2. Set colorSecondary for the storybook theme to a dark colour eg. #1a115a
3. Run storybook
4. hover/focus on unselected items within the sidemenu are now almost unreadable

System

Storybook Environment Info:

  System:
    OS: macOS 15.2
    CPU: (12) arm64 Apple M3 Pro
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.18.0 - /usr/local/bin/node
    npm: 10.8.2 - /usr/local/bin/npm <----- active
  Browsers:
    Chrome: 132.0.6834.84
    Edge: 131.0.2903.147
    Safari: 18.2
  npmPackages:
    @storybook/addon-a11y: ^8.4.7 => 8.5.0 
    @storybook/addon-docs: ^8.4.7 => 8.5.0 
    @storybook/addon-essentials: ^8.4.7 => 8.5.0 
    @storybook/addon-links: ^8.4.7 => 8.5.0 
    @storybook/addon-themes: ^8.4.7 => 8.5.0 
    @storybook/blocks: ^8.4.7 => 8.5.0 
    @storybook/html: ^8.4.7 => 8.5.0 
    @storybook/html-webpack5: ^8.4.7 => 8.5.0 
    @storybook/manager-api: ^8.4.7 => 8.5.0 
    @storybook/preview-api: ^8.4.7 => 8.5.0 
    @storybook/theming: ^8.4.7 => 8.5.0 
    storybook: ^8.4.7 => 8.5.0 
    storybook-addon-pseudo-states: ^4.0.2 => 4.0.2 
    storybook-addon-tag-badges: ^1.4.0 => 1.4.0 
    storybook-addon-turbo-build: ^2.0.1 => 2.0.1 
    storybook-dark-mode: ^4.0.2 => 4.0.2 
    storybook-preset-inline-svg: ^1.0.1 => 1.0.1

Additional context

No response

[msmx-mnakagawa]

(cc: @NickyBlissTui)
I have tried to make a simple PR fixing this issue.
#30287

If possible, could someone take a look into the PR?