Modernize UI to Support Host OS Theme Mode in Main Window

[lsd-techno]

Enhancement Request

To improve user experience and keep GateSwitchWay visually aligned with current desktop standards, update the main UI window to detect and support the host operating system's theme mode (light/dark).

Desired Actions:

• Refactor UI so it automatically switches between light and dark modes based on the OS settings.
• Ensure all UI elements (backgrounds, text, icons, etc.) adapt properly to both modes.
• Provide fallback or manual mode toggle if automatic detection fails.
• Test across supported platforms for consistency.

Motivation

This modernization enhances accessibility and usability while meeting the expectations of users on modern OS platforms.