Update custome translations to i18n and various improvements

src/components/language-selector.tsx

@@ -15,14 +15,14 @@ import { Label } from './ui/label';
 const LanguageSelector = ({ currentLanguage, onLanguageChange, t }: any) => {
   return (
     <div className="flex items-center gap-2">
-      <Label className="text-sm font-medium">{t.language}:</Label>
+      <Label className="text-sm font-medium">{t('language')}:</Label>
       <Select value={currentLanguage} onValueChange={onLanguageChange}>
         <SelectTrigger className="w-32">
           <SelectValue />
         </SelectTrigger>
         <SelectContent>
-          <SelectItem value="en">{t.english}</SelectItem>
-          <SelectItem value="de">{t.german}</SelectItem>
+          <SelectItem value="en">{t('english')}</SelectItem>
+          <SelectItem value="de">{t('german')}</SelectItem>
         </SelectContent>
       </Select>
     </div>