Improve tooltip contrast on dark mode (including flyouts and overlays)

## Description

The current tooltip colors have poor contrast in dark mode, which impacts readability and accessibility. This becomes especially problematic when tooltips appear on top of dark flyouts, where they can be nearly invisible.

## Expected behavior
1. Tooltips should maintain sufficient contrast against dark mode backgrounds.
2. When appearing over dark components like flyouts, tooltips should remain clearly readable.

## Screenshots of the issue