Support arbitrary screen resolution/sizes for theme editor / simulator / emulator

Is your feature request related to a problem? If so, please describe the problem.

I want to simulate / edit themes for screen sizes that are not supported by the current code.

Describe the feature / solution to your problem you'd like

I'd like to be able to specify the screen resolution if the device to simulate, without code changes and writing a driver class.

Options for setting resolution:

• config file, currently ignored by theme editor
• theme.yaml
• environment variable

Describe alternatives you've considered / and or tested

Writing a driver class for hardware that may not exist yet is onerous.

Screenshots / photos & mockups of the Turing screen
Add screenshots or photos/mockups of the rendering on the Turing screen to help explain your request.

Environment:

• Revision of this project: main
  commit 2fcdeb12f4f9a01d0968e98255818fb62fa1540b (HEAD -> simulate_arbitrary_screen_size, origin/main, origin/HEAD, main)
  Merge: c48637c 7aeed84
  Author: Matthieu Houdebine mat.houdebine@wanadoo.fr
  Date: Wed Jan 8 08:58:39 2025 +0100
• OS with version: Windows 10
• Python version: Python 3.12.1 (tags/v3.12.1:2305ca5, Dec 7 2023, 22:03:25) [MSC v.1937 64 bit (AMD64)] on win32
• Hardware: NA, happens to be using Intel CPU, see above

Additional context
Add any other context or screenshots about the feature request here.

Start by locating the theme editor and simulator/emulator entry points, then trace how the currently ignored config file and theme.yaml are read. Compare config-file, theme.yaml, and environment-variable options for specifying resolution. Done means arbitrary screen sizes work in the theme editor, simulator, and emulator without code changes or a driver class.