Sprint: pbi-55 (#156)

* ST-cmovs79lt: Schema + migratie PushSubscription model

Voeg PushSubscription model toe aan prisma/schema.prisma met
snake_case-conventie, relation field op User, en bijbehorende
migratie (push_subscriptions tabel, FK + index op user_id).

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

* ST-cmovs7e3o: web-push dependency + VAPID env vars feature-gated

Voeg web-push + @types/web-push toe aan package.json.
Registreer NEXT_PUBLIC_VAPID_PUBLIC_KEY, VAPID_PRIVATE_KEY,
VAPID_SUBJECT en INTERNAL_PUSH_SECRET als .optional() in lib/env.ts.
Documenteer alle vier in .env.example en README.

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

* ST-cmovs7jgr: lib/push-server.ts met sendPushToUser + stale-cleanup

Server-only push-lib met VAPID feature-gate, send naar alle
subscriptions van een user, en automatische cleanup bij 404/410.
Unit tests: success-pad, 410 verwijdert sub, 404 verwijdert sub,
andere errors loggen zonder delete.

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

* 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>

* ST-cmovs7ut4: actions/push.ts subscribeToPushAction + unsubscribeFromPushAction

Vervangt stub met volledige implementatie: requireUser via getSession,
demo-block, Zod-validatie, upsert met user_id-scoping en user-scoped
deleteMany. Tests (8): idempotentie, demo-block, unauthenticated, invalid input.

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

* ST-cmovs80c1: POST /api/internal/push/send met constant-time Bearer check

Route: 503 als INTERNAL_PUSH_SECRET uitstaat, 401 bij verkeerd secret
(timingSafeEqual), 400 bij invalid JSON, 422 bij Zod-fout, 204 bij succes.
push-server.ts: env-import vervangen door process.env om SESSION_SECRET
validatie tijdens build te omzeilen. Tests aangepast.

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

* ST-cmovs862j: Admin test-send route + public/sw.js service worker

POST /api/internal/push/test-send: requireAdmin check (redirect bij
niet-admin), optioneel body met defaults, roept sendPushToUser aan, 204.
public/sw.js: push-handler met showNotification, notificationclick met
same-origin guard, focus bestaand venster of openWindow.

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

* ST-cmovs8jvq: PushToggle component met 3 states + iOS-banner

Client component met states loading/unsupported/ios-needs-install/
denied/subscribed/unsubscribed. useEffect detecteert initial status,
permission-prompt alleen via user-click. iOS-banner NL, denied-uitleg,
subscribe/unsubscribe knoppen met sonner-toasts.

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

* ST-cmovs8psg: notifications-sheet + iOS meta-tags in layout

notifications-sheet.tsx: PushToggle onderin met sectie
'Notificatie-instellingen' en visuele scheidslijn.
app/layout.tsx: appleWebApp.capable, statusBarStyle en
mobile-web-app-capable meta-tags toegevoegd via Next.js Metadata API.
manifest.json had al display: standalone.

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

* ST-cmovs8vxj: docs/patterns/web-push.md pattern-documentatie

Architectuur-diagram, payload-shape, foutcodes, VAPID-config,
iOS-quirks, demo-users blokkade, trigger-voorbeelden (server +
HTTP) en admin-testroute curl-voorbeeld.

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

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/push-server.ts

@@ -0,0 +1,63 @@
+import 'server-only'
+
+import webpush from 'web-push'
+import { prisma } from '@/lib/prisma'
+
+export type PushPayload = {
+  title: string
+  body: string
+  url: string
+  tag?: string
+}
+
+const vapidReady =
+  !!process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY &&
+  !!process.env.VAPID_PRIVATE_KEY &&
+  !!process.env.VAPID_SUBJECT
+
+if (vapidReady) {
+  webpush.setVapidDetails(
+    process.env.VAPID_SUBJECT!,
+    process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY!,
+    process.env.VAPID_PRIVATE_KEY!,
+  )
+}
+
+export const enabled = vapidReady
+
+export async function sendPushToUser(userId: string, payload: PushPayload): Promise<void> {
+  if (!enabled) {
+    console.warn('[push-server] VAPID not configured — skipping push for user', userId)
+    return
+  }
+
+  const subs = await prisma.pushSubscription.findMany({ where: { user_id: userId } })
+  await Promise.allSettled(subs.map((sub) => sendOne(sub, payload)))
+}
+
+async function sendOne(
+  sub: { id: string; endpoint: string; p256dh: string; auth: string },
+  payload: PushPayload,
+): Promise<void> {
+  try {
+    await webpush.sendNotification(
+      { endpoint: sub.endpoint, keys: { p256dh: sub.p256dh, auth: sub.auth } },
+      JSON.stringify(payload),
+    )
+    await prisma.pushSubscription.update({
+      where: { id: sub.id },
+      data: { last_used_at: new Date() },
+    })
+  } catch (err: unknown) {
+    const status = (err as { statusCode?: number }).statusCode
+    if (status === 404 || status === 410) {
+      try {
+        await prisma.pushSubscription.delete({ where: { id: sub.id } })
+      } catch {
+        // already deleted by a concurrent request — ignore
+      }
+    } else {
+      console.error('[push-server] sendNotification error for endpoint', sub.endpoint, err)
+    }
+  }
+}