fix: configure CI database connection properly

- Add dotenv loading to Django settings
- Update CI workflow to use correct environment variables
- Set POSTGRES_* variables instead of DATABASE_URL
- Add environment variables to all Django management commands
- Fixes CI test failures due to database connection issues

remove_legacy_views.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+"""
+Script to remove legacy Verpachtung views from views.py
+"""
+
+import re
+import sys
+
+def remove_legacy_verpachtung_views():
+    with open('app/stiftung/views.py', 'r', encoding='utf-8') as f:
+        content = f.read()
+    
+    # Remove verpachtung_export function
+    export_pattern = r'@login_required\s+def verpachtung_export\([^)]+\):[^@]*?pass\s*\n\n'
+    content = re.sub(export_pattern, '', content, flags=re.DOTALL)
+    
+    # More aggressive pattern for verpachtung_export
+    export_pattern2 = r'@login_required\s+def verpachtung_export.*?(?=@login_required|def \w+.*?\(.*?\):|\Z)'
+    content = re.sub(export_pattern2, '', content, flags=re.DOTALL)
+    
+    # Remove comment and all verpachtung views until next comment
+    verpachtung_section_pattern = r'# Verpachtung Views.*?(?=# [A-Z][^#\n]*Views|\Z)'
+    content = re.sub(verpachtung_section_pattern, '', content, flags=re.DOTALL)
+    
+    with open('app/stiftung/views.py', 'w', encoding='utf-8') as f:
+        f.write(content)
+    
+    print("Legacy Verpachtung views removed from views.py")
+
+if __name__ == "__main__":
+    remove_legacy_verpachtung_views()