[Error] xdg-open doesn't work, opening browser link fails

**Describe the bug**

Apps trying to open link in browser fail.

**To Reproduce**

Run `xdg-open https://unity.com` in container.
It doesn't work (nothing happens).

The same command works fine on host.

Also, I was trying to make it work using `distrobox-host-exec`, but it seems to not work for me at all.
From examples `distrobox-host-exec --help`
running `distrobox-host-exec podman ps -a` shows nothing (no output) in container,
while on host `podman ps -a` works fine and gives the list of running containers.

To fully reproduce, create a new container and install Unity Hub:
```sh
distrobox create --name unity-box --image ubuntu:24.04
distrobox enter unity-box
cd
sudo apt update
sudo apt upgrade
sudo apt install libasound2t64 # it's needed for Unity Hub

# Unity Hub
wget -qO - https://hub.unity3d.com/linux/keys/public | gpg --dearmor | sudo tee /usr/share/keyrings/Unity_Technologies_ApS.gpg > /dev/null
sudo sh -c 'echo "deb [signed-by=/usr/share/keyrings/Unity_Technologies_ApS.gpg] https://hub.unity3d.com/linux/repos/deb stable main" > /etc/apt/sources.list.d/unityhub.list'
sudo apt update
sudo apt install unityhub

unityhub
```
It should open a window Unity Hub with buttons/links that you can click and see that they don't work
(nothing happens when you click them).

**Expected behavior**

I'm expecting to be able to log in using links from container's apps (like Unity Hub).

**Logs**
Cannot find any related logs to this issue in podman, verbose on `xdg-open` doesn't produce any additional output

**Desktop (please complete the following information):**
- Are you using podman, docker or lilipod?
podman
- Which version or podman, docker or lilipod?
podman 4.9.3
- Which version of distrobox?
1.7.0
- Which host distribution?
Ubuntu 24.04
- How did you install distrobox?
`sudo apt install distrobox`

**Additional context**
N/A

這個 issue 是關於 xdg-open 和 distrobox-host-exec 在容器內無法運作的問題。先檢查 distrobox 如何處理主機指令的執行，可能需要查看 distrobox-host-exec 腳本。檢查它與主機桌面環境及 xdg-open 的整合。按照描述在測試容器中重現這個 bug，然後追蹤執行流程，查看失敗發生在哪裡。

由索引模型根據 Issue 內容生成。