feat(ui): Liquid Glass + Aceternity 컴포넌트 도입 (clsx·framer-motion·tailwind-merge)

- LiquidGlass: GlassButton·GlassFilter (Apple Liquid Glass 효과)
- 3d-card-effect: 마우스 추적 3D 카드 래퍼
- sparkles-text: SparklesText·SparklesOverlay
- lib/utils.ts: cn() (clsx + tailwind-merge)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/utils.ts

@@ -0,0 +1,6 @@
+import { clsx, type ClassValue } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}