Round 19b: 10 Runtime Bug Fixes, Student Notebook Access, German Curriculum Types

Bug Fixes:
- Fixed duplicate i18n keys (notebooks.type_lined etc.)
- Fixed settings-view.tsx: studentsList undefined → students
- Fixed student-detail-view.tsx: pe.competencyId → pe.competency.id
- Fixed student-detail-view.tsx: locale variable not in scope
- Fixed student-detail-view.tsx: studentId/setStudent undefined
- Fixed notebooks-view.tsx: onClick={onAddPage} passing MouseEvent
- Fixed curriculum-coverage-view.tsx: Map import shadowing built-in
- Fixed api.ts: avatarUrl missing from AttendanceRecord/Report types
- Fixed badge-check.ts: invalid Prisma queries with wrong field names

Student Notebook Access:
- Students can create/view/edit their own notebooks
- Students see shared notebooks from teachers in enrolled classes
- Fixed handleCreateFromTemplate to use correct ownerType for students

German Curriculum Notebook Types (9 types):
- Deutschheft (lined, red), Matheheft (grid, blue), Sachbuch (grid, teal)
- Musikheft (music staff, emerald), Kunstheft (blank, purple)
- Englischheft (lined, amber), Geschichtsheft (lined, brown)
- Religionsheft (lined, orange), Sachkundeheft (lined+drawing, teal)

Environment Features:
- Papier gespart counter with tree calculation
- Eco badge on every notebook card
- Lehrplan-Heft curriculum badge on German types

60+ new i18n keys (DE/EN)

src/app/api/reports/route.ts

@@ -43,7 +43,7 @@ export async function GET(request: Request) {
       where,
       orderBy: { generatedAt: 'desc' },
       include: {
-        student: { select: { id: true, firstName: true, lastName: true } },
+        student: { select: { id: true, firstName: true, lastName: true, avatarUrl: true } },
         classGroup: { select: { id: true, name: true, gradeLevel: true } },
         schoolYear: { select: { id: true, label: true } },
         generatedByUser: {
@@ -116,7 +116,7 @@ export async function POST(request: Request) {
           : undefined,
       },
       include: {
-        student: { select: { id: true, firstName: true, lastName: true } },
+        student: { select: { id: true, firstName: true, lastName: true, avatarUrl: true } },
         classGroup: { select: { id: true, name: true } },
         schoolYear: { select: { id: true, label: true } },
         generatedByUser: {
@@ -186,7 +186,7 @@ export async function PUT(request: Request) {
       where: { id },
       data: updateData,
       include: {
-        student: { select: { id: true, firstName: true, lastName: true } },
+        student: { select: { id: true, firstName: true, lastName: true, avatarUrl: true } },
         classGroup: { select: { id: true, name: true, gradeLevel: true } },
         schoolYear: { select: { id: true, label: true } },
         generatedByUser: {