feat: complete header and dropdown redesign for professional look

- Redesign site header with multi-layer gradient overlays, decorative glows, dot pattern texture, responsive clamp font sizing, and animated ping online badge
- Add glass-dropdown CSS class with 60% opacity backdrop blur (20px) and smooth dropdownIn animation (scale + translate)
- Fix dropdown positioning with top-full for proper alignment under menu triggers
- Standardize all dropdowns (nav, top-header, color picker, language switcher) to use glass-dropdown class

src/components/language-switcher.tsx

@@ -58,8 +58,7 @@ export function LanguageSwitcher() {
 
       {open && (
         <div
-          className="absolute right-0 mt-1 min-w-[160px] rounded-xl shadow-xl z-50 py-2 border backdrop-blur-md"
-          style={{ backgroundColor: "color-mix(in srgb, var(--color-dropdown) 80%, transparent)", borderColor: "color-mix(in srgb, var(--color-text-muted) 10%, transparent)" }}
+          className="glass-dropdown absolute right-0 top-full mt-0.5 min-w-[160px] rounded-xl z-50 py-2"
         >
           {LOCALES.map((l) => (
             <button