feat: add multi-rack elevation view and switch icons

- add rack elevation view for one or multiple racks
- render front and rear device positions by rack unit
- show physical cabling below selected racks
- add site, location, rack, and empty-rack filters
- add network, leaf, spine, and aggregation switch icons
- add “Weitere Ansichten” navigation category

netbox_topology_views/urls.py

@@ -8,6 +8,7 @@ from . import models, views
 urlpatterns = (
     path("", RedirectView.as_view(url="topology/", permanent=True)),
     path("topology/", views.TopologyHomeView.as_view(), name="home"),
+    path("rack-elevation/", views.RackElevationView.as_view(), name="rack_elevation"),
     path("images/", views.TopologyImagesView.as_view(), name="images"),
     path("individualoptions/", views.TopologyIndividualOptionsView.as_view(), name="individualoptions"),