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

fix_verpachtung_references.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+"""
+Script to replace all remaining legacy Verpachtung references with LandVerpachtung
+"""
+
+import re
+
+def replace_verpachtung_references():
+    with open('app/stiftung/views.py', 'r', encoding='utf-8') as f:
+        content = f.read()
+    
+    # Replace Verpachtung.objects with LandVerpachtung.objects
+    content = re.sub(r'\bVerpachtung\.objects\b', 'LandVerpachtung.objects', content)
+    
+    # Replace legacy field names with new ones
+    content = re.sub(r'pachtzins_jaehrlich', 'pachtzins_pauschal', content)
+    
+    # Replace legacy field references in aggregates
+    content = re.sub(r"Sum\('verpachtung__pachtzins_jaehrlich'\)", "Sum('landverpachtung__pachtzins_pauschal')", content)
+    content = re.sub(r"Sum\('verpachtung__verpachtete_flaeche'\)", "Sum('landverpachtung__verpachtete_flaeche')", content)
+    
+    # Update related name references
+    content = re.sub(r"verpachtung_set", "landverpachtung_set", content)
+    content = re.sub(r"verpachtung_id", "land_verpachtung_id", content)
+    
+    with open('app/stiftung/views.py', 'w', encoding='utf-8') as f:
+        f.write(content)
+    
+    print("Updated all legacy Verpachtung references to use LandVerpachtung")
+
+if __name__ == "__main__":
+    replace_verpachtung_references()