fix: improve dark mode UI consistency in signin page (#23684)

web/app/signin/_header.tsx

@@ -1,7 +1,7 @@
 'use client'
 import React from 'react'
 import { useContext } from 'use-context-selector'
-import Select from '@/app/components/base/select/locale'
+import LocaleSigninSelect from '@/app/components/base/select/locale-signin'
 import Divider from '@/app/components/base/divider'
 import { languages } from '@/i18n-config/language'
 import type { Locale } from '@/i18n-config'
@@ -33,7 +33,7 @@ const Header = () => {
         />
         : <DifyLogo size='large' />}
       <div className='flex items-center gap-1'>
-        <Select
+        <LocaleSigninSelect
           value={locale}
           items={languages.filter(item => item.supported)}
           onChange={(value) => {