Round 19c: Professional Notebooks, Enhanced Timetable/Resources/Homework, Bug Fixes

Notebook Enhancements:
- Page numbering (auto page numbers at bottom)
- German-style margin lines on lined pages (rote Randlinie)
- Auto date stamp on new pages
- Sticker/stamp collection for educational rewards
- Page corner fold (dog-ear) on bookmarked pages
- Washi tape decorative strips

Timetable View:
- Weekly grid view (Mon-Fri, periods 1-6)
- Color-coded subjects
- Current period highlight
- Room/location display
- Drag-and-drop reschedule

Resource Library:
- Categories (worksheets, presentations, videos, links)
- Search/filter bar
- Resource preview cards with thumbnails
- Favorite/bookmark functionality

Homework View:
- Calendar view for due dates
- Submission status indicators
- Grade display for graded homework
- My Homework view for students

Settings Bug Fix:
- Fixed TabsContent outside Tabs component (caused runtime crash)

Drawing Canvas:
- Added ruler/straight edge tool

100+ new i18n keys (DE/EN)

src/components/settings-view.tsx

@@ -4199,8 +4199,6 @@ export default function SettingsView() {
               </CardContent>
             </Card>
           </TabsContent>
-        </Tabs>
-      </motion.div>
 
       {/* ── Backup Restore Confirmation ──────────────────────────── */}
       <AlertDialog open={!!restoreBackupId} onOpenChange={(open) => { if (!open) setRestoreBackupId(null); }}>
@@ -5185,6 +5183,8 @@ export default function SettingsView() {
       <TabsContent value="privacy">
         <PrivacyTab currentUser={currentUser} />
       </TabsContent>
+      </Tabs>
+    </motion.div>
     </motion.div>
   );
 }