[Feature Request]: Add a new Base theme Valyrian

### Guidelines

- [x] I have [searched the issue tracker for open and closed issues](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+sort%3Arelevance-desc) 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.
- [x] I have read and agree to follow the [rules](https://docs.freetubeapp.io/community/rules/).

### Problem Description

Can you add a new base theme for FT called Valyrian. This is theme that is based on Arc

### Proposed Solution

In the base theme settings there would be a Valyrian option like with other themes

### Alternatives Considered

Adding the original Arc Dark theme:

https://github.com/horst3180/arc-theme

### Issue Labels

visual improvement

### FreeTube Version

v0.24.0 Beta

### Operating System Version

Ubuntu 24.04 LTS

### Installation Method

Flathub

### Upload screenshots or videos

### Additional Information

Background color:
Hex: #0e1b28
RGB: 14, 27, 40

Sidepanel
Hex: 0b1823
RGB: 11, 24, 35

Accent colors for the theme (Optional):
Option 1: Hex #bf562f
RGB: 191, 86, 47

Option 2: Hex #3b4f61
RGB: 59, 79, 97

Option 3: Hex #244766
RGB: 36, 71, 102

Link for the GTK theme:
https://www.opendesktop.org/p/1955721