feat: Enhance UI with system theme, refined headers, and new layout

- layout: Auto-detect system theme on first visit
- header: Refined layout (centered, uppercase subtitle, inline help)
- categories: Compact 'Soft Pill' design with improved focus state
- data: Reorganized Zellij to CLI Tools
- lint: Fixed various linting issues

src/components/app/CategorySection.tsx

@@ -80,7 +80,6 @@ function CategorySectionComponent({
                 y: 0,
                 opacity: 1,
                 duration: 0.5,
-                stagger: 0.025,
                 ease: 'power2.out',
                 delay: delay + 0.1,
                 force3D: true