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/static_dev/css/app.scss

@@ -26,3 +26,32 @@ html[data-netbox-color-mode=dark] #visgraph {
     cursor: pointer;
   }
 }
+
+.rack-elevation-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(34rem, 1fr));
+  gap: 1rem;
+}
+
+.rack-card {
+  border: 1px solid var(--tblr-border-color, #ced4da);
+  border-radius: .4rem;
+  background: var(--tblr-bg-surface, #fff);
+  padding: 1rem;
+}
+
+.rack-card > header { display: flex; justify-content: space-between; margin-bottom: .75rem; }
+.rack-faces { display: grid; grid-template-columns: 1fr 1fr; gap: .75rem; }
+.rack-face-title { text-align: center; font-size: .75rem; text-transform: uppercase; margin-bottom: .25rem; }
+.rack-frame { display: flex; height: calc(var(--rack-units) * 14px); min-height: 280px; max-height: 70vh; border: 4px solid #3b4654; background: repeating-linear-gradient(to top, rgba(127,127,127,.14) 0, rgba(127,127,127,.14) 1px, transparent 1px, transparent calc(100% / var(--rack-units))); }
+.rack-unit-labels { width: 2rem; display: flex; flex-direction: column; justify-content: space-around; font-size: .55rem; text-align: center; color: var(--tblr-secondary, #667382); }
+.rack-device-area { position: relative; flex: 1; border-left: 1px solid #3b4654; }
+.rack-device { position: absolute; left: 3px; right: 3px; min-height: 2px; overflow: hidden; padding: 1px 5px; border: 2px solid #1685fc; border-radius: 3px; background: #162e45; color: #fff; line-height: 1.1; text-decoration: none; }
+.rack-device:hover { filter: brightness(1.25); color: #fff; z-index: 2; }
+.rack-device span, .rack-device small { display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.rack-device small { font-size: .6rem; opacity: .8; }
+
+@media (max-width: 700px) {
+  .rack-elevation-grid { grid-template-columns: 1fr; }
+  .rack-faces { grid-template-columns: 1fr; }
+}