chore: change hex colors to tailwind bariables

src/shared/ui/Button/Button.svelte

@@ -138,11 +138,11 @@ const variantStyles: Record<ButtonVariant, string> = {
         'text-neutral-400 dark:text-neutral-400',
         'border border-transparent',
         // Hover (inactive) — semi-transparent lift, no bg-paper token
-        'hover:bg-white/50 dark:hover:bg-[#1e1e1e]/50',
+        'hover:bg-paper/50 dark:hover:bg-dark-card/50',
         'hover:text-neutral-900 dark:hover:text-neutral-100',
         'hover:border-black/5 dark:hover:border-white/10',
         // Press
-        'active:bg-white/70 dark:active:bg-[#1e1e1e]/70',
+        'active:bg-paper/70 dark:active:bg-dark-card/70',
         // Disabled
         'disabled:text-neutral-300 dark:disabled:text-neutral-600',
         'disabled:cursor-not-allowed',
@@ -169,7 +169,7 @@ const iconSizeStyles: Record<ButtonSize, string> = {
 const activeStyles: Partial<Record<ButtonVariant, string>> = {
     secondary: 'bg-paper dark:bg-paper shadow-sm border-black/20 dark:border-white/20',
     tertiary:
-        'bg-paper dark:bg-[#1e1e1e] border-black/10 dark:border-white/10 shadow-sm text-neutral-900 dark:text-neutral-100',
+        'bg-paper dark:bg-dark-card border-black/10 dark:border-white/10 shadow-sm text-neutral-900 dark:text-neutral-100',
     ghost: 'bg-transparent dark:bg-transparent text-brand dark:text-brand',
     outline: 'bg-surface dark:bg-paper border-brand',
     icon: 'bg-paper dark:bg-paper text-brand border-black/5 dark:border-white/10',