Add Geschichte (History) wiki-style feature with reorganized navigation

🆕 NEW FEATURES:
- Wiki-style Geschichte (History) section with rich text editor
- Image upload support for history pages
- Quill.js rich text editor with formatting options
- Slug-based URLs for SEO-friendly history pages
- Image galleries with descriptions and alt-text support

🔧 MODELS:
- GeschichteSeite: Main history pages with rich content
- GeschichteBild: Image attachments for history pages
- Auto-generated slugs, sorting, publishing controls

📝 TEMPLATES:
- geschichte/liste.html: Card-based overview of all history pages
- geschichte/detail.html: Full page view with image gallery
- geschichte/form.html: Rich text editor for creating/editing pages
- geschichte/bild_form.html: Image upload interface

🎨 UI IMPROVEMENTS:
- Reorganized navigation menu into logical groups:
  * Menschen & Finanzen (People & Finance)
  * Immobilien & Land (Real Estate & Land)
  * Verwaltung (Administration)
  * Geschichte (History)
- More compact menu design saving horizontal space
- Better grouping with dropdown headers

🛠️ TECHNICAL:
- Rich text editor with Quill.js integration
- Image upload with validation and optimization
- Permission-based access controls
- Responsive design for all screen sizes
- Proper breadcrumb navigation
- Auto-slug generation from titles

app/stiftung/urls.py

@@ -385,4 +385,10 @@ urlpatterns = [
         views.quarterly_confirmation_reset,
         name="quarterly_confirmation_reset",
     ),
+    # Geschichte URLs
+    path("geschichte/", views.geschichte_list, name="geschichte_list"),
+    path("geschichte/neu/", views.geschichte_create, name="geschichte_create"),
+    path("geschichte/<slug:slug>/", views.geschichte_detail, name="geschichte_detail"),
+    path("geschichte/<slug:slug>/bearbeiten/", views.geschichte_edit, name="geschichte_edit"),
+    path("geschichte/<slug:slug>/bild-upload/", views.geschichte_bild_upload, name="geschichte_bild_upload"),
 ]