feat(ui/deployment): consolidate sites/areas/instances into Topology page

Single /deployment/topology page replaces /deployment/instances (legacy URL
preserved as a secondary @page directive) and the /admin/areas* CRUD pages.
TreeView with Site → Area → Instance, V1–V7 visual guide (bi-building /
bi-diagram-3 / bi-box), always-visible empty containers, search dim, F2
inline area rename, and right-click context menus per node kind (Add Area,
Move to Area…, lifecycle actions, etc.).

Adds AreaService.MoveAreaAsync with cycle prevention, same-site enforcement,
and name-collision check at the new parent. Instance rename intentionally
out of scope — UniqueName is the site-side actor identity, requires its own
design pass.

src/ScadaLink.CentralUI/Components/Pages/Deployment/InstanceConfigure.razor

@@ -15,7 +15,7 @@
 
 <div class="container-fluid mt-3">
     <div class="d-flex align-items-center mb-3">
-        <button class="btn btn-outline-secondary btn-sm me-3" @onclick="GoBack">&larr; Back to Instances</button>
+        <button class="btn btn-outline-secondary btn-sm me-3" @onclick="GoBack">&larr; Back to Topology</button>
         <h4 class="mb-0">Configure Instance</h4>
     </div>
 
@@ -257,7 +257,7 @@
         _loading = false;
     }
 
-    private void GoBack() => NavigationManager.NavigateTo("/deployment/instances");
+    private void GoBack() => NavigationManager.NavigateTo("/deployment/topology");
 
     private async Task<string> GetCurrentUserAsync()
     {