fix(landing): replace language cycle button with dropdown selector

The landing page language switcher cycled to the next language on every
click. It is now a dropdown listing all 13 languages; the cycling button
variant is removed from the LanguageSwitcher component.

frontend/src/components/ui/language-switcher.tsx

@@ -1,7 +1,6 @@
 "use client";
 
 import { Globe } from "lucide-react";
-import { Button } from "@/components/ui/button";
 import {
   Select,
   SelectContent,
@@ -28,49 +27,27 @@ const languages: { value: Locale; label: string; flag: string }[] = [
 ];
 
 interface LanguageSwitcherProps {
-  variant?: "select" | "button";
+  className?: string;
 }
 
-export function LanguageSwitcher({ variant = "select" }: LanguageSwitcherProps) {
+export function LanguageSwitcher({ className }: LanguageSwitcherProps) {
   const { locale, setLocale } = useI18n();
-
-  if (variant === "button") {
-    const currentIndex = languages.findIndex((l) => l.value === locale);
-    const nextIndex = (currentIndex + 1) % languages.length;
-    const nextLang = languages[nextIndex];
-    const currentLang = languages[currentIndex];
-
-    return (
-      <Button
-        variant="ghost"
-        size="sm"
-        onClick={() => setLocale(nextLang.value)}
-        className="gap-1.5 text-muted-foreground hover:text-foreground"
-      >
-        <Globe className="h-4 w-4" />
-        <span className="text-sm">{currentLang.flag}</span>
-        <span className="text-xs font-medium uppercase">{currentLang.value}</span>
-      </Button>
-    );
-  }
+  const current = languages.find((l) => l.value === locale) ?? languages[0];
 
   return (
     <Select value={locale} onValueChange={(v) => setLocale(v as Locale)}>
-      <SelectTrigger className="w-[150px] h-9">
+      <SelectTrigger className={className} aria-label="Change language">
         <SelectValue>
           <span className="flex items-center gap-2">
             <Globe className="h-4 w-4" />
-            {languages.find((l) => l.value === locale)?.flag}{" "}
-            {languages.find((l) => l.value === locale)?.label}
+            <span>{current.flag}</span>
+            <span>{current.label}</span>
           </span>
         </SelectValue>
       </SelectTrigger>
-      <SelectContent>
+      <SelectContent align="start">
         {languages.map((lang) => (
-          <SelectItem
-            key={lang.value}
-            value={lang.value}
-          >
+          <SelectItem key={lang.value} value={lang.value}>
             <span className="flex items-center gap-2">
               <span>{lang.flag}</span>
               <span>{lang.label}</span>