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/top-header.tsx

@@ -67,8 +67,7 @@ export async function TopHeader() {
                 Administration
               </summary>
               <div
-                className="absolute right-0 mt-1 min-w-[180px] 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-[180px] rounded-xl z-50 py-2"
               >
                 <Link href="/admin" className="dropdown-item">
                   Admin panel
@@ -90,8 +89,7 @@ export async function TopHeader() {
               <span className="-ml-2 font-semibold" style={{ color: "var(--color-navbar-text, var(--color-text))" }}>{session.user.name}</span>
             </summary>
             <div
-              className="absolute right-0 mt-1 min-w-[200px] 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-[200px] rounded-xl z-50 py-2"
             >
               <Link href="/me" className="dropdown-item">
                 My dashboard