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/app/api/notebooks/[id]/pages/[pageId]/route.ts

@@ -0,0 +1,145 @@
+import { NextResponse } from 'next/server';
+import { z } from 'zod';
+import { db } from '@/lib/db';
+import { getSession } from '@/lib/auth';
+
+// ── PUT: Update a page ──
+const updatePageSchema = z.object({
+  textContent: z.string().optional().nullable(),
+  drawingData: z.string().optional().nullable(),
+  background: z
+    .enum(['lined', 'grid', 'blank', 'dotted', 'music'])
+    .optional(),
+  isBookmark: z.boolean().optional(),
+  title: z.string().optional().nullable(),
+});
+
+export async function PUT(
+  request: Request,
+  { params }: { params: Promise<{ id: string; pageId: string }> }
+) {
+  try {
+    const session = await getSession();
+    if (!session?.user) {
+      return NextResponse.json({ error: 'Not authenticated' }, { status: 401 });
+    }
+
+    const { id, pageId } = await params;
+
+    const page = await db.notebookPage.findUnique({
+      where: { id: pageId },
+      include: { notebook: true },
+    });
+
+    if (!page || page.notebookId !== id) {
+      return NextResponse.json({ error: 'Page not found' }, { status: 404 });
+    }
+
+    if (page.notebook.deletedAt) {
+      return NextResponse.json(
+        { error: 'Notebook has been deleted' },
+        { status: 400 }
+      );
+    }
+
+    if (page.notebook.ownerId !== session.user.id) {
+      return NextResponse.json({ error: 'Access denied' }, { status: 403 });
+    }
+
+    const body = await request.json();
+    const parsed = updatePageSchema.safeParse(body);
+    if (!parsed.success) {
+      return NextResponse.json(
+        { error: 'Validation failed', details: parsed.error.issues },
+        { status: 400 }
+      );
+    }
+
+    const updatedPage = await db.notebookPage.update({
+      where: { id: pageId },
+      data: parsed.data,
+    });
+
+    // Audit log
+    await db.auditLog.create({
+      data: {
+        userId: session.user.id,
+        schoolId: page.notebook.schoolId,
+        action: 'UPDATE',
+        entityType: 'NotebookPage',
+        entityId: pageId,
+        metadata: JSON.stringify({
+          notebookId: id,
+          pageNumber: page.pageNumber,
+          updatedFields: Object.keys(parsed.data),
+        }),
+      },
+    });
+
+    return NextResponse.json(updatedPage);
+  } catch (error) {
+    console.error('Notebook page update error:', error);
+    return NextResponse.json(
+      { error: 'Internal server error' },
+      { status: 500 }
+    );
+  }
+}
+
+// ── DELETE: Delete a page ──
+export async function DELETE(
+  request: Request,
+  { params }: { params: Promise<{ id: string; pageId: string }> }
+) {
+  try {
+    const session = await getSession();
+    if (!session?.user) {
+      return NextResponse.json({ error: 'Not authenticated' }, { status: 401 });
+    }
+
+    const { id, pageId } = await params;
+
+    const page = await db.notebookPage.findUnique({
+      where: { id: pageId },
+      include: { notebook: true },
+    });
+
+    if (!page || page.notebookId !== id) {
+      return NextResponse.json({ error: 'Page not found' }, { status: 404 });
+    }
+
+    if (page.notebook.ownerId !== session.user.id) {
+      return NextResponse.json({ error: 'Access denied' }, { status: 403 });
+    }
+
+    await db.notebookPage.delete({
+      where: { id: pageId },
+    });
+
+    // Audit log
+    await db.auditLog.create({
+      data: {
+        userId: session.user.id,
+        schoolId: page.notebook.schoolId,
+        action: 'DELETE',
+        entityType: 'NotebookPage',
+        entityId: pageId,
+        metadata: JSON.stringify({
+          notebookId: id,
+          pageNumber: page.pageNumber,
+        }),
+      },
+    });
+
+    return NextResponse.json({
+      message: 'Page deleted',
+      id: pageId,
+    });
+  } catch (error) {
+    console.error('Notebook page delete error:', error);
+    return NextResponse.json(
+      { error: 'Internal server error' },
+      { status: 500 }
+    );
+  }
+}