Phase 9d: Notification cron + multilingual templates + status badges

Backend (school-service):
  - notification_log table with UNIQUE(event_id, lead_days, audience,
    channel) for idempotent re-runs. Status enum sent/failed/skipped.
  - internal/notifications/templates.go: per-event-type × audience ×
    lead-day-bucket × language templates in 8 languages (de/en/tr/ar/
    uk/ru/pl/fr). Fallback chain (lang→de, eventType→andere) so we
    never miss a render.
  - service.go scans cal_school_event for events whose
    (start_date - runDate) appears in notification_lead_days. For each
    due (audience, channel) tuple it dispatches via POST to the
    Matrix/Email upstreams owned by the colleague's services.
    Empty URL → status='skipped', logged for visibility.
  - dispatcher.go handles the POST, parent-recipient lookup (joins
    parent_account + parent_child + cal_school_event.affected_class_ids),
    and writeLog with the unique constraint dropping duplicate runs.
  - main.go runs a 1-hour ticker; when time.Hour()==6 it invokes the
    scanner for today. Idempotent so transient restarts don't double-
    send.
  - POST /calendar/notifications/run-now for manual trigger + backfill
    (?date=YYYY-MM-DD).
  - GET /calendar/events/:id/notifications returns notification_log
    rows scoped to the owning teacher.
  - MATRIX_SERVICE_URL + EMAIL_SERVICE_URL env vars added (default
    empty = stub mode).

Frontend (studio-v2):
  - NotificationStatus component fetches /events/:id/notifications and
    renders coloured badges per (lead, audience, channel, status).
  - DayDetail mounts NotificationStatus inside each event card when
    notify_parents or notify_students is set.

Tests:
  - 6 new Go unit tests for bucketFor + Render (de/tr/fallback paths)
    + substitute(class_suffix). 89 subtests gesamt.
  - 2 new Playwright tests: badge render with mocked log, hidden when
    notifications are off.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

studio-v2/e2e/schulkalender.spec.ts

@@ -10,6 +10,7 @@ interface MockOpts {
   config?: { user_id: string; bundesland: string } | null
   holidays?: unknown[]
   events?: unknown[]
+  notificationLog?: unknown[]
 }
 
 async function mockCalendarApi(page: Page, opts: MockOpts = {}) {
@@ -83,6 +84,16 @@ async function mockCalendarApi(page: Page, opts: MockOpts = {}) {
       }),
     })
   })
+
+  // Phase 9d: per-event notification_log + manual trigger. NotificationStatus
+  // component fetches the log when an event has notify_parents/students.
+  await page.route(/\/api\/school\/calendar\/events\/[^/]+\/notifications$/, async (route) => {
+    return route.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify(opts.notificationLog ?? []) })
+  })
+  await page.route(/\/api\/school\/calendar\/notifications\/run-now.*/, async (route) => {
+    return route.fulfill({ status: 200, contentType: 'application/json',
+      body: '{"date":"2026-05-22","sent":0,"failed":0,"skipped":0,"already_logged":0}' })
+  })
 }
 
 test.describe('Schulkalender — Bundesland Wizard', () => {
@@ -249,3 +260,58 @@ test.describe('Schulkalender — Schuljahres-Rollover', () => {
     await expect(page.getByText('2 Abschlussklassen entfernt')).toBeVisible()
   })
 })
+
+// ==========================================================================
+// Phase 9d — Notification-Status im DayDetail
+// ==========================================================================
+
+test.describe('Schulkalender — Notification-Status', () => {
+  test('shows sent badge for delivered reminders', async ({ page }) => {
+    const todayIso = new Date().toISOString().slice(0, 10)
+    await mockCalendarApi(page, {
+      config: { user_id: 'dev', bundesland: 'DE-NI' },
+      events: [{
+        id: 'e1', created_by_user_id: 'dev',
+        title: 'Pruefe Test-Event', event_type: 'projekttag',
+        is_school_free: false,
+        start_date: todayIso, end_date: todayIso,
+        affected_class_ids: [], visible_to_parents: true,
+        notify_parents: true, notify_students: false,
+        notification_lead_days: [7, 1],
+      }],
+      notificationLog: [
+        { lead_days: 7, audience: 'parents', channel: 'email', status: 'sent', run_date: '2026-05-15', created_at: '2026-05-15T06:00:00Z' },
+        { lead_days: 1, audience: 'parents', channel: 'email', status: 'skipped', run_date: '2026-05-21', created_at: '2026-05-21T06:00:00Z' },
+      ],
+    })
+    await page.goto('/schulkalender')
+    await page.waitForLoadState('networkidle')
+    await page.getByTestId(`day-${todayIso}`).click()
+    await expect(page.getByTestId('day-detail')).toBeVisible()
+
+    const status = page.getByTestId('notif-status-e1')
+    await expect(status).toBeVisible()
+    await expect(status.getByText(/7 Tage.*Eltern.*email/)).toBeVisible()
+    await expect(status.getByText(/1 Tag.*Eltern.*email/)).toBeVisible()
+  })
+
+  test('hides notification status when notifications are off', async ({ page }) => {
+    const todayIso = new Date().toISOString().slice(0, 10)
+    await mockCalendarApi(page, {
+      config: { user_id: 'dev', bundesland: 'DE-NI' },
+      events: [{
+        id: 'e2', created_by_user_id: 'dev',
+        title: 'Stilles Event', event_type: 'andere',
+        is_school_free: false,
+        start_date: todayIso, end_date: todayIso,
+        affected_class_ids: [], visible_to_parents: true,
+        notify_parents: false, notify_students: false,
+        notification_lead_days: [],
+      }],
+    })
+    await page.goto('/schulkalender')
+    await page.waitForLoadState('networkidle')
+    await page.getByTestId(`day-${todayIso}`).click()
+    await expect(page.getByTestId('notif-status-e2')).toHaveCount(0)
+  })
+})