Let users see and unsubscribe their own push devices

Fixes duplicate/triple OS notifications on machines where more than
one browser (e.g. both Chrome and Edge on Windows) independently got
notification permission for the site — each held its own valid
subscription, so every event pushed to both.

Adds a userAgent column (captured client-side at subscribe time,
display-only) and a Settings > Account section listing a user's own
subscribed browsers with a friendly label plus an unsubscribe button,
backed by new GET/DELETE /api/push/subscriptions endpoints scoped to
the caller's own rows.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gh2UXUQUVBWroWEnn1FLFG

src/lib/push/service.ts

@@ -1,4 +1,4 @@
-import { eq, inArray } from "drizzle-orm";
+import { eq, inArray, and } from "drizzle-orm";
 import { db } from "@/lib/db/client";
 import { pushSubscriptions, users } from "@/lib/db/schema";
 import type { TicketDTO, MessageDTO } from "@/lib/tickets/types";
@@ -10,13 +10,17 @@ export interface PushSubscriptionKeys {
 }
 
 /** Re-subscribing from the same browser (e.g. after clearing site data and re-granting) overwrites the old row via the endpoint's unique constraint, rather than accumulating stale duplicates. */
-export async function savePushSubscription(userId: string, sub: PushSubscriptionKeys): Promise<void> {
+export async function savePushSubscription(
+  userId: string,
+  sub: PushSubscriptionKeys,
+  userAgent?: string,
+): Promise<void> {
   await db
     .insert(pushSubscriptions)
-    .values({ userId, endpoint: sub.endpoint, p256dh: sub.keys.p256dh, auth: sub.keys.auth })
+    .values({ userId, endpoint: sub.endpoint, p256dh: sub.keys.p256dh, auth: sub.keys.auth, userAgent })
     .onConflictDoUpdate({
       target: pushSubscriptions.endpoint,
-      set: { userId, p256dh: sub.keys.p256dh, auth: sub.keys.auth },
+      set: { userId, p256dh: sub.keys.p256dh, auth: sub.keys.auth, userAgent },
     });
 }
 
@@ -24,6 +28,22 @@ export async function deletePushSubscriptionByEndpoint(endpoint: string): Promis
   await db.delete(pushSubscriptions).where(eq(pushSubscriptions.endpoint, endpoint));
 }
 
+/** A user's own subscribed devices/browsers, for the "manage notifications" settings list — never exposes the endpoint/keys, only what's useful to tell rows apart. */
+export async function listPushSubscriptionsForUser(userId: string) {
+  const rows = await db.query.pushSubscriptions.findMany({
+    where: eq(pushSubscriptions.userId, userId),
+    orderBy: (t, { desc }) => desc(t.createdAt),
+  });
+  return rows.map((r) => ({ id: r.id, userAgent: r.userAgent, createdAt: r.createdAt }));
+}
+
+/** Deletes one of the current user's own subscriptions by id — scoped so a user can only ever remove their own. */
+export async function deleteOwnPushSubscription(userId: string, id: string): Promise<void> {
+  await db
+    .delete(pushSubscriptions)
+    .where(and(eq(pushSubscriptions.id, id), eq(pushSubscriptions.userId, userId)));
+}
+
 async function sendPushToUsers(userIds: string[], payload: { title: string; body: string; url: string }): Promise<void> {
   if (userIds.length === 0 || !ensureVapidConfigured()) return;