Dropdown menu does not match dark mode theme

[anujchoudhary-17]

When configuring a new provider in BrowserOS (Dark Mode enabled), the dropdown menu appears in light mode while the rest of the UI is in dark mode.

Steps to Reproduce:

1. Switch to Dark Mode in BrowserOS.
2. Go to Settings
3. In the Left Panel, Select "BrowserOS AI"
4. Click on "Add custom provider"
5. Open the Provider Type dropdown.

Expected Behavior: The dropdown should follow the dark mode theme and display a dark background with light text.

Actual Behavior: The dropdown opens in light mode (white background with dark text), breaking UI consistency.