dark mode doesn't actually works, half the UI ignores it and it resets on refresh

[avinxshKD]

The toggle sets data-theme="dark" on html but nothing reads it. components use inline hardcoded colors everywhere so the attribute does nothing. the dark mode button itself is backgroundColor: '#eee'.

Also resets on every refresh, no localStorage, no prefers-color-scheme. needs a proper CSS variable system and persistence.

what needs:

1. define a CSS variable system (--bg-primary, --text-primary, etc.) with light/dark values
2. replace all inline hardcoded colors with CSS vars
3. persist to localStorage
4. read prefers-color-scheme on first load

[avinxshKD]

@pradeeban what do you think, any suggestions? would love to know