Support Soplos Linux in the installer

A user reported that the installer (`install.danklinux.com`) currently rejects Soplos Linux because it identifies itself as `ID=soplos` in `/etc/os-release`.

Soplos is based on Debian Testing, and DMS works correctly when using the existing Debian Testing repositories manually. The installer could treat Soplos as Debian Testing to provide the same one-command installation experience.

Original report by @graplo:
https://github.com/AvengeMedia/dms-plugin-registry/issues/721

Original report

Hi DankLinux / DMS team,

First of all, I absolutely love DMS! It has become one of my favorite projects, and I really appreciate the work you’ve put into creating this shell from scratch—it’s fantastic.

I’ve been testing DMS on Soplos Linux (https://soplos.org/), a great Debian Testing-based distribution made by Sergi. Sergi does an amazing job maintaining it, even packaging custom optimized kernels tailored for different CPU architectures.

Right now, running the easy installer (curl -fsSL [https://install.danklinux.com](https://install.danklinux.com) | sh) on Soplos gives an "unsupported distribution" message, simply because Soplos identifies itself as soplos in /etc/os-release.

However, DMS runs flawlessly on Soplos when using the Debian Testing OBS repositories manually:

```bash
# Native quickshell from Debian
sudo apt update
sudo apt install quickshell

# DankLinux repository
curl -fsSL https://download.opensuse.org/repositories/home:AvengeMedia:danklinux/Debian_Testing/Release.key | \
sudo gpg --dearmor -o /etc/apt/keyrings/danklinux.gpg
echo "deb [signed-by=/etc/apt/keyrings/danklinux.gpg] https://download.opensuse.org/repositories/home:/AvengeMedia:/danklinux/Debian_Testing/ /" | \
sudo tee /etc/apt/sources.list.d/danklinux.list

# DMS repository
curl -fsSL https://download.opensuse.org/repositories/home:/AvengeMedia:/dms/Debian_Testing/Release.key | \
sudo gpg --dearmor -o /etc/apt/keyrings/avengemedia-dms.gpg
echo "deb [signed-by=/etc/apt/keyrings/avengemedia-dms.gpg] https://download.opensuse.org/repositories/home:/AvengeMedia:/dms/Debian_Testing/ /" | \
sudo tee /etc/apt/sources.list.d/avengemedia-dms.list

sudo apt update
sudo apt install dms
```

I made a video showcasing the full experience and how well it runs here:

https://www.youtube.com/watch?v=06rrdO1ZIKY

It would be awesome if you could include Soplos Linux in the installer detection script to route it to the Debian Testing packages. This would make it super easy for new Soplos users to discover and enjoy DMS with just the single curl command.

Thanks again for building such an incredible shell!

Locate the installer detection script used by install.danklinux.com and read how Debian Testing distributions are identified. Verify the Soplos /etc/os-release value is routed to the Debian Testing repositories, then test the installer path and confirm it no longer reports Soplos as unsupported.

Written by the indexing model from the issue text.