[Feature Request]: Rosé Pine Theme

### Guidelines

- [X] I have searched the issue tracker for [open](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aopen+is%3Aissue) and [closed](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+is%3Aclosed) issues that are similar to the feature request I want to file, without success.
- [X] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [X] This issue contains only one feature request.

### Problem Description

I would like a Rosé Pine theme for FreeTube. The specification for Rosé Pine can be found on [the website](https://rosepinetheme.com/).

### Proposed Solution

The addition of a Rosé Pine base theme, and "Love", "Gold", "Rose", "Pine", "Foam", and "Iris" accent options.

### Alternatives Considered

#3145 could be an alternative, allowing users who want a Rosé Pine theme to set it themselves within the app.

### Issue Labels

improvement to existing feature, visual improvement

### Additional Information

I'm not sure how much free time I have at the moment, but if I have the time and motivation, I'll have a look at implementing this myself. If there's any documentation on adding themes I would appreciate that.

Start with the Rosé Pine specification linked in the issue and review alternative issue #3145 for context on user-defined themes. Locate FreeTube's existing theme implementation and add a base Rosé Pine theme with Love, Gold, Rose, Pine, Foam, and Iris accent options; done means users can select these options in the app.

Written by the indexing model from the issue text.