fix(notifications): a notice's button is said when shown, like its text

An action label was translated when the notice was raised, so after a language switch a live
toast or center row read in one language with its button in the other. The access-requests nudge
no longer re-issues on a switch for it. New tests: the button and a server refusal follow a
switch.

frontend/src/modules/notifications/NotificationsPanel.tsx

@@ -393,7 +393,7 @@ export default function NotificationsPanel() {
             : !n.dismissed
               ? liveActions(n).map((action, i) => ({
                   id: `action${i}`,
-                  label: action.label,
+                  label: sayNotif(action.label, t),
                   onSelect: () => {
                     action.onClick();
                     dismissClient(n.id);
@@ -570,7 +570,7 @@ export default function NotificationsPanel() {
 }
 
 /** A client notice's live actions (they do not survive a reload): its action, then the lesser one. */
-function liveActions(n: ClientNotif): { label: string; onClick: () => void }[] {
+function liveActions(n: ClientNotif): NonNullable<ClientNotif["action"]>[] {
   return [n.action, n.secondaryAction].filter((a) => a !== undefined);
 }
 
@@ -920,7 +920,7 @@ function ClientActivityRow({
             <div className="mt-1 flex flex-wrap gap-x-4">
               {liveActions(n).map((action, i) => (
                 <Button
-                  key={action.label}
+                  key={i}
                   variant="link"
                   className="text-sm"
                   // The first is the row's own: Enter on the row runs it.
@@ -930,7 +930,7 @@ function ClientActivityRow({
                     dismissClient(n.id);
                   }}
                 >
-                  {action.label}
+                  {sayNotif(action.label, t)}
                 </Button>
               ))}
             </div>