Enhance search functionality with case-insensitive title search, security improvements, and comprehensive tests

- Add case-insensitive search across all fields (inhalt, titel, geltungsbereich)
- Include Vorgabe.titel field in search scope for better coverage
- Implement comprehensive input validation against SQL injection and XSS
- Add German error messages for validation failures
- Escape search terms in templates to prevent XSS attacks
- Add input length limits and character validation
- Preserve user input on validation errors for better UX
- Add comprehensive test suite with 27 tests covering all functionality
- Test security features: XSS prevention, SQL injection protection, input validation
- Test edge cases: expired content, multiple documents, German umlauts
- Ensure all search fields work correctly with case-insensitive matching

pages/views.py

@@ -23,7 +23,7 @@ def validate_search_input(search_term):
     search_term = re.sub(r'<[^>]*>', '', search_term)
     
     # Allow only alphanumeric characters, spaces, and basic punctuation
-    # This prevents SQL injection and other malicious input
+    # This prevents SQL injection and other malicious input while allowing useful characters
     if not re.match(r'^[a-zA-Z0-9äöüÄÖÜß\s\-\.\,\:\;\!\?\(\)\[\]\{\}\"\']+$', search_term):
         raise ValidationError("Ungültige Zeichen im Suchbegriff")