feat(frontend): i18n shared state components + UsersAdminPage + CHANGELOG

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/Toast.tsx

@@ -1,6 +1,8 @@
+import { useTranslation } from 'react-i18next';
 import { useToast } from '@/hooks/useToast';
 
 export function ToastViewport(): JSX.Element {
+  const { t } = useTranslation();
   const { toasts, dismiss } = useToast();
   return (
     <div
@@ -8,9 +10,9 @@ export function ToastViewport(): JSX.Element {
       aria-atomic="true"
       className="fixed bottom-xl right-xl z-50 flex flex-col gap-sm w-[320px] pointer-events-none"
     >
-      {toasts.map((t) => {
-        const isError = t.kind === 'error';
-        const isSuccess = t.kind === 'success';
+      {toasts.map((toast) => {
+        const isError = toast.kind === 'error';
+        const isSuccess = toast.kind === 'success';
         const surface = isError
           ? 'bg-paper text-ink border border-hairline border-l-4 border-l-bloom-deep'
           : isSuccess
@@ -18,18 +20,18 @@ export function ToastViewport(): JSX.Element {
             : 'bg-paper text-ink border border-hairline border-l-4 border-l-primary';
         return (
           <div
-            key={t.id}
+            key={toast.id}
             role="status"
             data-testid="toast"
-            data-kind={t.kind}
+            data-kind={toast.kind}
             className={`pointer-events-auto rounded-none px-md py-sm text-[14px] leading-[1.4] ${surface}`}
           >
             <div className="flex items-start justify-between gap-sm">
-              <span className="flex-1">{t.message}</span>
+              <span className="flex-1">{toast.message}</span>
               <button
                 type="button"
-                onClick={() => dismiss(t.id)}
-                aria-label="Dismiss notification"
+                onClick={() => dismiss(toast.id)}
+                aria-label={t('toast.dismiss')}
                 className="text-current opacity-70 hover:opacity-100"
               >
                 ×