Improve Neovide Terminal Color Configuration

### Is your feature related to a problem?

If the terminal colors are not configured, the appearance of the terminal inside Neovide is not very appealing. By default, it looks like this:


### Describe the new feature

Add a way for users to customize **Neovide's terminal colors** . This would allow them to define specific colors for the terminal that will be used exclusively within **Neovide** , _regardless_ of their overall terminal color settings.

### Additional context
There are several approaches to implement this feature:

- Create an external plugin similar to AstroCore that allows users to set Neovide-specific options as tables.

- Integrate this feature directly into the Neovide recipe.

- Incorporate this feature into AstroCore, enhancing the integration between AstroNvim and Neovide, and allowing us to proudly highlight this feature.

No files or tests are named. Start by reading the Neovide recipe and the AstroCore integration points, then compare the external-plugin, recipe, and AstroCore approaches described in the issue. Done means users can configure terminal colors used only in Neovide, independently of their general terminal settings.

Written by the indexing model from the issue text.