fix(layout): stop the page fade firing on every language toggle

Switching locale (e.g. cn -> ms or cn -> vi) read as a ~220ms flicker
because the <AnimatePresence> wrapping <main> was keyed on the full
pathname. Changing the language prefix changed the key, so AnimatePresence
treated the swap as a route change and re-ran the page fade transition.

Strip the language prefix when computing the key so only real route
changes drive AnimatePresence. Same translations render in place, no
opacity dip. Measured opacity stays at 1 across a cn -> ms switch in
the browser instead of dipping to 0 and back.

src/layouts/PublicLayout.tsx

@@ -928,7 +928,12 @@ export function PublicLayout() {
       >
         <AnimatePresence mode="wait" initial={false}>
           <m.div
-            key={`${pathname}${search}`}
+            // Key on the language-stripped path so switching locale (e.g.
+            // /cn/browse → /ms/browse) is not seen as a route change. Without
+            // this the AnimatePresence fade-out/fade-in (~220ms) fires on every
+            // language toggle and reads as a flicker, especially for ms / vi
+            // where the nav width also changes and re-runs layout.
+            key={`${stripLangPrefix(pathname)}${search}`}
             variants={pageTransition}
             initial="initial"
             animate="enter"