fix: ensure mobile menu and language dropdown appear in front of hero banner video (raised z-indexes for overlays)

- Navbar: z-[999]
- Mobile menu container/panel: z-[1000]/z-[1001]
- Cart drawer: z-[980]/z-[990]
- LanguageSwitcher dropdown/backdrop: z-[1010]/z-[1020]
- Updated comments
- Mobile menu (incl. when clicking language inside it) now reliably stacks above the mobile banner video and other content.

components/LanguageSwitcher.tsx

@@ -31,12 +31,12 @@ export default function LanguageSwitcher() {
         <>
           {/* Backdrop */}
           <div 
-            className="fixed inset-0 z-40" 
+            className="fixed inset-0 z-[1010]" 
             onClick={() => setIsOpen(false)} 
           />
           
           {/* Dropdown */}
-          <div className="absolute right-0 top-full mt-2 z-50 w-44 rounded-2xl border border-[#c99a2e]/20 bg-[#fbf7ef] shadow-2xl overflow-hidden">
+          <div className="absolute right-0 top-full mt-2 z-[1020] w-44 rounded-2xl border border-[#c99a2e]/20 bg-[#fbf7ef] shadow-2xl overflow-hidden">
             {languages.map((lang) => (
               <button
                 key={lang.code}