Fix theme consistency, i18n completeness, CSS variable naming, and hardcoded strings

src/app/admin/users/[id]/edit/page.tsx

@@ -96,7 +96,7 @@ export default async function AdminUserEdit({
       <form action={updateUser} className="admin-card">
         <input type="hidden" name="id" value={user.id} />
 
-        <div className="grid cols-2">
+        <div className="grid grid-cols-1 gap-4 md:grid-cols-2">
           <label>
             {t("email")}
             <input name="mail" type="email" defaultValue={user.mail ?? ""} maxLength={500} />

src/app/admin/users/[id]/page.tsx

@@ -79,7 +79,7 @@ export default async function AdminUserDetail({
 
       <section className="mt-6">
         <h2 className="admin-section-title">{t("detail.actions")}</h2>
-        <div className="grid cols-2">
+        <div className="grid grid-cols-1 gap-4 md:grid-cols-2">
           <form action={giveCurrency} className="admin-card">
             <input type="hidden" name="userId" value={user.id} />
             <h3 className="text-sm font-bold text-[var(--color-text)] m-0 mb-3">{t("detail.giveCurrency")}</h3>