feat: Round 22 - Exam calendar, parent portal, teacher grading, deep styling

- Exam calendar integration: Plan Exam button, countdown badges, exam filter
- Parent portal: Children overview, illness approvals, grades, attendance
- Teacher grading: Stylus annotation, AI review, bulk grading mode
- Deep schlaukopf crawling: AI-powered content extraction from schlaukopf.de
- Dashboard: Upcoming exams, AI tips section
- Settings: AI provider config, virtual character toggle, management tabs
- Layout: Favorites section, notification badges on sidebar items
- Auth: VICE_PRINCIPAL demo account, feature showcase
- Attendance: Illness report integration
- Assessments: Plan exam button, AI test generation
- Fixed schoolId auto-detect in counseling and disciplinary APIs
- Added MessageSquare import to settings-view
- 150+ new i18n keys

src/lib/api.ts

@@ -560,6 +560,27 @@ export function createGradingScheme(data: {
   return apiPost<GradingScheme>('/api/grading', data);
 }
 
+/* ── Grading Annotations ─────────────────────────────────────────── */
+
+export interface GradingAnnotation {
+  id: string;
+  annotationData: string;
+  annotationImage: string | null;
+}
+
+export function fetchGradingAnnotation(assessmentId: string, studentId: string): Promise<{ annotation: GradingAnnotation | null }> {
+  return apiGet(`/api/grading/annotate?assessmentId=${assessmentId}&studentId=${studentId}`);
+}
+
+export function saveGradingAnnotation(data: {
+  assessmentId: string;
+  studentId: string;
+  annotationData: string;
+  annotationImage?: string;
+}): Promise<{ annotation: GradingAnnotation }> {
+  return apiPost('/api/grading/annotate', data);
+}
+
 /* ── Reports ──────────────────────────────────────────────────────── */
 
 export interface ReportSection {
@@ -1648,7 +1669,7 @@ export function fetchCalendarEvents(schoolId: string, month: string): Promise<Ca
 
 /* ── Calendar Events (Custom) ──────────────────────────────────── */
 
-export type CalendarEventItemType = 'assessment' | 'lesson' | 'reminder';
+export type CalendarEventItemType = 'assessment' | 'lesson' | 'reminder' | 'exam';
 
 export interface RecurrencePattern {
   type: 'none' | 'daily' | 'weekly' | 'monthly' | 'yearly';