CompetenceTrack v8 - Complete UI/UX redesign, Digital Notebooks, Drawing Canvas, Demo Data Cleanup

Features:
- Complete UI/UX redesign for tablet/stylus optimization
- Digital Notebook system (lined, grid, blank, dotted, music, calligraphy)
- Drawing Canvas with stylus/pen support, pressure sensitivity
- Art class mode with tutorial guides and shape templates
- Demo data one-click cleanup for production transition
- Subject-specific notebook filtering
- Environmental messaging (Papier sparen, Umwelt schützen)
- 44px minimum touch targets for tablet
- No emojis - Lucide icons throughout
- 700+ i18n keys (German/English)
- Notebook types: lined, grid, blank, dotted, music, calligraphy
- Drawing tools: pencil, pen, line, rectangle, circle, eraser
- Undo/redo, color picker, stroke width, export PNG
- Archive/unarchive notebooks
- White backgrounds throughout
- Emerald accent color theme

Backend:
- Notebook CRUD API routes
- Drawing CRUD API routes
- Demo data cleanup API
- Prisma schema with Notebook, NotebookPage, Drawing models
- isDemo flags on all new models

src/lib/store.ts

@@ -22,7 +22,9 @@ export type ViewName =
   | 'behavior'
   | 'coverage'
   | 'rubrics'
-  | 'comments';
+  | 'comments'
+  | 'notebooks'
+  | 'drawing';
 
 export interface CurrentUser {
   id: string;