Brightness slider works only in Settings panel, not on desktop or apps

[Haris16-code]

📝 Description

The Brightness option in BJH OS settings currently only works inside the settings panel and has no effect on the desktop or apps. Adjusting the slider should control the display brightness throughout the OS.

Goals

• Make the brightness slider functional across the entire desktop and apps.
• Ensure changes reflect immediately when the slider is adjusted.
• Save the brightness setting so it persists after reload.

Tasks

• Debug the current brightness slider implementation.
• Fix JavaScript code to apply brightness changes outside settings as well.
• Apply brightness changes to relevant CSS or display settings.
• Test on desktop and mobile devices.
• Ensure settings are saved to local storage or BJH OS configuration.

Expected Result

1. Users move the brightness slider.
2. Screen brightness changes in real-time across the desktop and apps.
3. Settings persist across sessions.

Acceptance Criteria

• Slider works on desktop and mobile browsers.
• Changes are immediate and smooth.
• No console errors appear when adjusting brightness.
• Brightness affects the entire OS, not just the settings panel.