Add test push notification flow

lib/notification-api.ts

@@ -35,6 +35,15 @@ export async function deletePushSubscription(endpoint: string) {
   if (!response.ok) throw new Error("Unable to delete push subscription.");
 }
 
+export async function sendTestPushNotification(endpoint: string) {
+  const response = await fetch("/api/notifications/test", {
+    method: "POST",
+    headers: { "content-type": "application/json" },
+    body: JSON.stringify({ endpoint }),
+  });
+  if (!response.ok) throw new Error("Unable to send test notification.");
+}
+
 export function decodeBase64UrlKey(value: string) {
   const padding = "=".repeat((4 - (value.length % 4)) % 4);
   const base64 = `${value}${padding}`.replace(/-/g, "+").replace(/_/g, "/");