Add Web Push warning notification backend

types/notifications.ts

@@ -0,0 +1,23 @@
+import type { Language } from "@/lib/i18n";
+import type { Province } from "@/types/province";
+
+export interface PushSubscriptionKeys {
+  p256dh: string;
+  auth: string;
+}
+
+export interface BrowserPushSubscription {
+  endpoint: string;
+  expirationTime?: number | null;
+  keys: PushSubscriptionKeys;
+}
+
+export interface WarningPushSubscription {
+  endpoint: string;
+  subscription: BrowserPushSubscription;
+  province: Province;
+  language: Language;
+  enabled: boolean;
+  createdAt: string;
+  updatedAt: string;
+}