feat: runtime accent color picker with 6 presets

Replace all hardcoded #c8ff00 / rgba(200,255,0,...) with CSS custom
properties (--accent, --accent-rgb) so the accent color updates live.
Add themeStore (Zustand + localStorage) with 6 presets (Лайм, Синий,
Розовый, Фиолет, Оранж, Минт). Add ThemeApplier component that syncs
CSS vars on load. Add color picker UI section in ExtraTab.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/components/Queue/QueueCard.tsx

@@ -75,7 +75,7 @@ export default function QueueCard() {
                 data-idx={i}
                 draggable
                 className="q-item flex items-center gap-2 px-4 py-2 border-b border-white/[0.07] last:border-b-0 cursor-pointer hover:bg-surface2 transition-colors duration-100 select-none relative sm:px-3"
-                style={{ background: active ? 'rgba(200,255,0,0.04)' : undefined }}
+                style={{ background: active ? 'rgba(var(--accent-rgb),0.04)' : undefined }}
                 onClick={(e) => handleQueueClick(e, i)}
                 onDragStart={(e) => onDragStart(i, e.currentTarget)}
                 onDragEnd={(e) => onDragEnd(e.currentTarget)}