ST-cmovs7ouz: lib/push-client.ts client-side push helpers + stub actions/push.ts

Client-side helpers: isPushSupported, isIOSSafari, isStandalonePWA,
urlBase64ToUint8Array, subscribeToPush, unsubscribeFromPush.
Stub actions/push.ts zodat imports resolven (implementatie volgt
in volgende taak). Unit tests voor urlBase64ToUint8Array.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/push-client.ts

@@ -0,0 +1,50 @@
+import { subscribeToPushAction, unsubscribeFromPushAction } from '@/actions/push'
+
+export function isPushSupported(): boolean {
+  return typeof window !== 'undefined' &&
+    'serviceWorker' in navigator &&
+    'PushManager' in window
+}
+
+export function isIOSSafari(): boolean {
+  if (typeof window === 'undefined') return false
+  const ua = navigator.userAgent
+  return /iPhone|iPad/.test(ua) && !/CriOS|FxiOS/.test(ua)
+}
+
+export function isStandalonePWA(): boolean {
+  if (typeof window === 'undefined') return false
+  return (
+    window.matchMedia('(display-mode: standalone)').matches ||
+    !!(navigator as Navigator & { standalone?: boolean }).standalone
+  )
+}
+
+export function urlBase64ToUint8Array(base64: string): Uint8Array<ArrayBuffer> {
+  const padding = '='.repeat((4 - (base64.length % 4)) % 4)
+  const base64Std = (base64 + padding).replace(/-/g, '+').replace(/_/g, '/')
+  const rawData = atob(base64Std)
+  const buf = new Uint8Array(rawData.length)
+  for (let i = 0; i < rawData.length; i++) buf[i] = rawData.charCodeAt(i)
+  return buf
+}
+
+export async function subscribeToPush(publicKey: string): Promise<PushSubscription> {
+  const reg = await navigator.serviceWorker.register('/sw.js', { updateViaCache: 'none' })
+  await navigator.serviceWorker.ready
+  const sub = await reg.pushManager.subscribe({
+    userVisibleOnly: true,
+    applicationServerKey: urlBase64ToUint8Array(publicKey),
+  })
+  await subscribeToPushAction(sub.toJSON() as Parameters<typeof subscribeToPushAction>[0])
+  return sub
+}
+
+export async function unsubscribeFromPush(): Promise<void> {
+  const reg = await navigator.serviceWorker.getRegistration()
+  const sub = await reg?.pushManager.getSubscription()
+  if (sub) {
+    await sub.unsubscribe()
+    await unsubscribeFromPushAction({ endpoint: sub.endpoint })
+  }
+}