Linux: selecting tty device fails | auto open does work

Describe the bug
Selecting a specific tty device fails to open. Auto-open does work

To Reproduce
Steps to reproduce the behavior:

1. run python3 configure.py
2. selct the tty device
3. save and run

Expected behavior
Open the tty device with the correct path.

Logs

(.venv)user@host turing-smart-screen-python][(HEAD 3.9.6)]$ 08.11.2025 19:48:06 [INFO] Loading theme Digital_CPU_0.96Inch from res/themes/Digital_CPU_0.96Inch/theme.yaml
08.11.2025 19:48:06 [DEBUG] Static COM port: ttyACM0
08.11.2025 19:48:06 [ERROR] Cannot open COM port ttyACM0: [Errno 2] could not open port ttyACM0
^C
(.venv)user@host turing-smart-screen-python][(HEAD  3.9.6)]$ python3 configure.py
(.venv)user@host turing-smart-screen-python][(HEAD 3.9.6)]$ 08.11.2025 19:48:26 [INFO] Loading theme Digital_CPU_0.96Inch from res/themes/Digital_CPU_0.96Inch/theme.yaml
08.11.2025 19:48:26 [DEBUG] Auto detected COM port: /dev/ttyACM0

Environment:

• Smart screen model [e.g. Turing 5", XuanFang 3.5”]
• Revision of this project: 3.9.6
• OS with version: Archlinux
• Python version [e.g. Python 3.10]
• Hardware: x86

Additional context
The path handling is not correct. The drop down menu misses the /dev/ path in front.

Start with configure.py and reproduce the difference between selecting ttyACM0 and auto-detection, which returns /dev/ttyACM0. Trace the selected value into serial-port opening and verify that saving a selected device preserves the correct path and allows the screen to start.