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/components/settings-view.tsx

@@ -667,7 +667,7 @@ function BadgeManagementTab() {
               <Select value={awardForm.studentId} onValueChange={(v) => setAwardForm(f => ({ ...f, studentId: v }))}>
                 <SelectTrigger><SelectValue placeholder={t('action.select')} /></SelectTrigger>
                 <SelectContent className="max-h-48">
-                  {studentsList.map(s => <SelectItem key={s.id} value={s.id}>{s.firstName} {s.lastName}</SelectItem>)}
+                  {students.map(s => <SelectItem key={s.id} value={s.id}>{s.firstName} {s.lastName}</SelectItem>)}
                 </SelectContent>
               </Select>
             </div>