Flips the theme: updates data-theme, persists the choice to localStorage under theme, and fires THEME_CHANGE_EVENT so any mounted UI (e.g. ThemeToggle's icon) can resync.
data-theme
theme
Flips the theme: updates
data-theme, persists the choice to localStorage undertheme, and fires THEME_CHANGE_EVENT so any mounted UI (e.g. ThemeToggle's icon) can resync.