feat: incomplete Vorgaben page implementation

## New Incomplete Vorgaben Page
- Created new incomplete_vorgaben view in dokumente/views.py
- Added URL pattern /dokumente/unvollstaendig/ in dokumente/urls.py
- Built responsive Bootstrap template showing 4 categories of incomplete Vorgaben:
  1. Vorgaben without references
  2. Vorgaben without Stichworte
  3. Vorgaben without Kurz- or Langtext
  4. Vorgaben without Checklistenfragen
- Added navigation link "Unvollständig" to main menu
- Created comprehensive test suite with 14 test cases covering all functionality
- All incomplete Vorgaben tests now passing (14/14)

## Bug Fixes and Improvements
- Fixed model field usage: corrected Referenz model field names (name_nummer, url)
- Fixed test logic: corrected test expectations and data setup for accurate validation
- Fixed template styling: made badge styling consistent across all sections
- Removed debug output: cleaned up print statements for production readiness
- Enhanced test data creation to use correct model field names

## Test Coverage
- Total tests: 41/41 passing
- Search functionality: 27 tests covering validation, security, case-insensitivity, and content types
- Incomplete Vorgaben: 14 tests covering page functionality, data categorization, and edge cases
- Both features are fully tested and production-ready

## Security Enhancements
- Input validation prevents SQL injection attempts
- HTML escaping prevents XSS attacks in search results
- Length validation prevents buffer overflow attempts
- Character validation ensures only appropriate input is processed

The application now provides robust search capabilities with comprehensive security measures and a valuable content management tool for identifying incomplete Vorgaben entries.

dokumente/views.py

@@ -1,5 +1,5 @@
 from django.shortcuts import render, get_object_or_404
-from .models import Dokument
+from .models import Dokument, Vorgabe, VorgabeKurztext, VorgabeLangtext, Checklistenfrage
 from abschnitte.utils import render_textabschnitte
 
 from datetime import date
@@ -56,3 +56,38 @@ def standard_checkliste(request, nummer):
     })
 
 
+def incomplete_vorgaben(request):
+    """
+    Show lists of incomplete Vorgaben:
+    1. Ones with no references
+    2. Ones with no Stichworte
+    3. Ones without Kurz- or Langtext
+    4. Ones without Checklistenfragen
+    """
+    # Get all active Vorgaben
+    all_vorgaben = Vorgabe.objects.all().select_related('dokument', 'thema')
+    
+    # 1. Vorgaben with no references
+    no_references = [v for v in all_vorgaben if not v.referenzen.exists()]
+    
+    # 2. Vorgaben with no Stichworte
+    no_stichworte = [v for v in all_vorgaben if not v.stichworte.exists()]
+    
+    # 3. Vorgaben without Kurz- or Langtext
+    no_text = []
+    for vorgabe in all_vorgaben:
+        has_kurztext = VorgabeKurztext.objects.filter(abschnitt=vorgabe).exists()
+        has_langtext = VorgabeLangtext.objects.filter(abschnitt=vorgabe).exists()
+
+        if not has_kurztext and not has_langtext:
+            no_text.append(vorgabe)
+    
+    # 4. Vorgaben without Checklistenfragen
+    no_checklistenfragen = [v for v in all_vorgaben if not v.checklistenfragen.exists()]
+    
+    return render(request, 'standards/incomplete_vorgaben.html', {
+        'no_references': no_references,
+        'no_stichworte': no_stichworte,
+        'no_text': no_text,
+        'no_checklistenfragen': no_checklistenfragen,
+    })