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>

__tests__/api/push-send.test.ts

@@ -0,0 +1,75 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+
+vi.mock('server-only', () => ({}))
+
+const { mockSendPushToUser } = vi.hoisted(() => ({
+  mockSendPushToUser: vi.fn(),
+}))
+
+vi.mock('@/lib/push-server', () => ({
+  sendPushToUser: mockSendPushToUser,
+  enabled: true,
+}))
+
+vi.hoisted(() => {
+  process.env.INTERNAL_PUSH_SECRET = 'a-valid-secret-that-is-at-least-32-chars'
+})
+
+import { POST } from '@/app/api/internal/push/send/route'
+
+const VALID_BODY = {
+  userId: 'user-1',
+  payload: { title: 'Hello', body: 'World', url: '/dashboard' },
+}
+const SECRET = 'a-valid-secret-that-is-at-least-32-chars'
+
+function makeRequest(body: unknown, bearer?: string) {
+  return new Request('http://localhost/api/internal/push/send', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      ...(bearer !== undefined ? { Authorization: bearer } : {}),
+    },
+    body: JSON.stringify(body),
+  })
+}
+
+beforeEach(() => {
+  vi.clearAllMocks()
+  mockSendPushToUser.mockResolvedValue(undefined)
+})
+
+describe('POST /api/internal/push/send', () => {
+  it('returns 401 without authorization header', async () => {
+    const res = await POST(makeRequest(VALID_BODY))
+    expect(res.status).toBe(401)
+    expect(mockSendPushToUser).not.toHaveBeenCalled()
+  })
+
+  it('returns 401 with wrong bearer secret', async () => {
+    const res = await POST(makeRequest(VALID_BODY, 'Bearer wrong-secret'))
+    expect(res.status).toBe(401)
+  })
+
+  it('returns 422 with invalid body', async () => {
+    const res = await POST(makeRequest({ userId: '', payload: {} }, `Bearer ${SECRET}`))
+    expect(res.status).toBe(422)
+    expect(mockSendPushToUser).not.toHaveBeenCalled()
+  })
+
+  it('returns 204 and calls sendPushToUser on success', async () => {
+    const res = await POST(makeRequest(VALID_BODY, `Bearer ${SECRET}`))
+    expect(res.status).toBe(204)
+    expect(mockSendPushToUser).toHaveBeenCalledWith('user-1', VALID_BODY.payload)
+  })
+
+  it('returns 400 for invalid JSON', async () => {
+    const req = new Request('http://localhost/api/internal/push/send', {
+      method: 'POST',
+      headers: { Authorization: `Bearer ${SECRET}`, 'Content-Type': 'application/json' },
+      body: 'not-json',
+    })
+    const res = await POST(req)
+    expect(res.status).toBe(400)
+  })
+})