feat(mobile): optimize mobile layout, navigation, and spacing

- Implement MobileBottomNav for native thumb-optimized usage
- Simplify Header overlay on mobile
- Add dynamic max() padding to ReferencesSlider for mobile view
- Condense vertical spacing in Footer for mobile devices
- Update layout.tsx to pad main content for bottom nav

components/blocks/ReferencesSlider.tsx

@@ -101,7 +101,7 @@ export function ReferencesSlider(props: ReferencesSliderProps) {
           onMouseLeave={onMouseLeave}
           onMouseUp={onMouseUp}
           onMouseMove={onMouseMove}
-          className={`flex gap-6 overflow-x-auto pb-12 pt-4 px-[calc((100vw-min(100%,1280px))/2)] [scrollbar-width:none] [-ms-overflow-style:none] [&::-webkit-scrollbar]:hidden ${isDragging ? 'cursor-grabbing snap-none' : 'cursor-grab snap-x snap-mandatory'}`}
+          className={`flex gap-6 overflow-x-auto pb-12 pt-4 px-[max(1rem,calc((100vw-1280px)/2))] md:px-[max(2rem,calc((100vw-1280px)/2))] lg:px-[max(2.5rem,calc((100vw-1280px)/2))] [scrollbar-width:none] [-ms-overflow-style:none] [&::-webkit-scrollbar]:hidden ${isDragging ? 'cursor-grabbing snap-none' : 'cursor-grab snap-x snap-mandatory'}`}
         >
           {references.map((ref, i) => {
             const imgSrc = (ref.image && typeof ref.image === 'object' && ref.image.url)