Round 22: Exam Calendar, Tablet Grading, Student Achievements, Notification Center, Announcements, Styling

- Exam Calendar View: Teacher exam planning with calendar integration
  - Teachers create/modify exams, admin full CRUD, students read-only
  - CalendarEvent integration, 2-week warning, AI test availability badge
  - Monthly/weekly calendar view, list view, statistics

- Tablet Grading View: Stylus annotation and AI grading audit
  - HTML5 Canvas with PointerEvent pressure sensitivity
  - Tool palette: pen, highlighter, eraser, text, stamp
  - Quick grade buttons (German 1-6 scale)
  - AI grading audit with detailed feedback and suggestions

- Student Achievements View: Badges, XP, leaderboard
  - Badge collection grid with category filters
  - Level/XP system with progress bars
  - Leaderboard with opt-in
  - Daily/weekly challenges

- Student Study Planner View: Pomodoro timer, weekly schedule
  - Pomodoro timer with focus score
  - Weekly study schedule with drag-and-drop
  - AI study recommendations
  - Session history and statistics

- Notification Center View: Categories, filters, bulk actions
  - 6 categories, 4 priority levels
  - Real-time polling (10 seconds)
  - Preferences with quiet hours
  - Statistics charts

- School Announcements View: CRUD, read receipts
  - 6 announcement types with gradient headers
  - Pin-to-top, read receipts, target audience
  - Admin/teacher create, students/parents view

- Bug fixes: AnnouncementRead model user relation, User API schoolId field
- i18n: 200+ new keys, breadcrumb navigation fixes
- Styling: Gradient headers, animations, hover effects across all new views

src/app/api/users/[id]/route.ts

@@ -9,6 +9,7 @@ const updateUserSchema = z.object({
   email: z.string().email().optional(),
   role: z.enum(['TEACHER', 'SCHOOL_ADMIN', 'SUPER_ADMIN', 'VICE_PRINCIPAL']).optional(),
   locale: z.string().optional(),
+  schoolId: z.string().optional(),
 });
 
 export async function GET(