Enhanced quarterly confirmation system with approval workflow and export improvements

Features added:
- ✅ Fixed quarterly confirmation approval system with URL pattern
- ✅ Added re-approval and status reset functionality for quarterly confirmations
- ✅ Synchronized quarterly approval status with support payment system
- ✅ Enhanced Destinataer export with missing fields (anrede, titel, mobil)
- ✅ Added quarterly confirmation data and documents to export system
- ✅ Fixed address field display issues in destinataer template
- ✅ Added quarterly statistics dashboard to support payment lists
- ✅ Implemented duplicate support payment prevention and cleanup
- ✅ Added visual indicators for quarterly-linked support payments

Technical improvements:
- Enhanced create_quarterly_support_payment() with duplicate detection
- Added get_related_support_payment() method to VierteljahresNachweis model
- Improved quarterly confirmation workflow with proper status transitions
- Added computed address property to Destinataer model
- Fixed template field mismatches (anrede, titel, mobil vs strasse, plz, ort)
- Enhanced backup system with operation tracking and cancellation

Workflow enhancements:
- Quarterly confirmations now properly sync with support payments
- Single support payment per destinataer per quarter (no duplicates)
- Approval button works for both eingereicht and geprueft status
- Reset functionality allows workflow restart
- Export includes complete quarterly data with uploaded documents

app/static.backup.20250924_232511/README.md

@@ -0,0 +1,11 @@
+# Static Files Directory
+
+This directory contains static files for the Django application.
+
+## Structure:
+- `css/` - Custom CSS files
+- `js/` - Custom JavaScript files  
+- `img/` - Image assets
+- `fonts/` - Font files
+
+Static files are collected to `staticfiles/` directory during deployment via `python manage.py collectstatic`.