fix(auth): take the push subscription off on every sign-out button

Only the menu's sign-out removed this browser's push subscription. The
sign-out buttons on the registration page and the profile take-over page,
which exist so someone else can use the browser next, left it behind, and
the next person kept seeing the last account's reminders. All three now
go through one signOutRequest.

The browser's own subscription is now removed only once the server has
confirmed the sign-out; the server row still goes first, while the
session can name it. A refused sign-out stores the row again, so the
person who is still signed in keeps push. The logout test pins the new
order and the refusal.

The helper file is renamed web-push-subscription.ts, since it now also
saves a subscription for the settings card.

src/components/settings/web-push-card.tsx

@@ -10,7 +10,10 @@ import { SettingsCardActions } from "@/components/settings/_card-actions";
 import { SettingsCardHeader } from "@/components/settings/_card-header";
 import { useTranslations } from "@/lib/i18n/context";
 import { apiFetchRaw } from "@/lib/api/api-fetch";
-import { unsubscribeWebPush } from "@/lib/notifications/web-push-unsubscribe";
+import {
+  saveWebPushSubscription,
+  unsubscribeWebPush,
+} from "@/lib/notifications/web-push-subscription";
 
 /** Convert a URL-safe base64 string to an ArrayBuffer (for VAPID key). */
 function urlBase64ToArrayBuffer(base64String: string): ArrayBuffer {
@@ -38,27 +41,6 @@ export function needsHomeScreen(): boolean {
   return appleTouch && !window.matchMedia("(display-mode: standalone)").matches;
 }
 
-/**
- * Store this browser's subscription for the signed-in account. Also run for a
- * subscription the browser already holds, so a row the server lost or gave
- * to another account on this browser comes back, and a channel switched off
- * by failed sends is turned on again.
- */
-function saveSubscription(subscription: PushSubscription): Promise<Response> {
-  const subJson = subscription.toJSON();
-  return apiFetchRaw("/api/notifications/web-push", {
-    method: "POST",
-    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({
-      endpoint: subJson.endpoint,
-      keys: {
-        p256dh: subJson.keys?.p256dh ?? "",
-        auth: subJson.keys?.auth ?? "",
-      },
-    }),
-  });
-}
-
 type Unsupported = "browser" | "install" | null;
 
 export function WebPushCard() {
@@ -94,7 +76,11 @@ export function WebPushCard() {
         if (registration) {
           const subscription = await registration.pushManager.getSubscription();
           setIsSubscribed(!!subscription);
-          if (subscription) void saveSubscription(subscription).catch(() => {});
+          // Sent again on every open: the server may have lost the row or
+          // switched the channel off, and the browser cannot tell.
+          if (subscription) {
+            void saveWebPushSubscription(subscription).catch(() => null);
+          }
         }
       } catch {
         // Ignore errors during check
@@ -133,7 +119,7 @@ export function WebPushCard() {
         applicationServerKey: urlBase64ToArrayBuffer(vapidPublicKey),
       });
 
-      const res = await saveSubscription(subscription);
+      const res = await saveWebPushSubscription(subscription);
       if (res.ok) {
         setIsSubscribed(true);
         setMsg(t("settings.webPushSubscribed"));