feat(m9/T24b): move-data-connection UI dialog + action

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Design/DataConnections.razor

@@ -42,6 +42,12 @@
 
     <ToastNotification @ref="_toast" />
 
+    <MoveDataConnectionDialog @bind-IsVisible="_showMoveDialog"
+                              ConnectionId="_moveConnectionId"
+                              ConnectionName="@_moveConnectionName"
+                              SiteOptions="MoveTargetSiteOptions()"
+                              OnMoved="OnConnectionMoved" />
+
     @if (_loading)
     {
         <LoadingSpinner IsLoading="true" />
@@ -124,6 +130,12 @@
                                         Edit
                                     </button>
                                 </li>
+                                <li>
+                                    <button class="dropdown-item"
+                                            @onclick="() => OpenMoveDialog(node.Connection!)">
+                                        Move to Site…
+                                    </button>
+                                </li>
                                 <li><hr class="dropdown-divider" /></li>
                                 <li>
                                     <button class="dropdown-item text-danger"
@@ -150,6 +162,10 @@
                             @onclick='() => NavigationManager.NavigateTo($"/design/connections/{node.Connection!.Id}/edit")'>
                         Edit
                     </button>
+                    <button class="dropdown-item"
+                            @onclick="() => OpenMoveDialog(node.Connection!)">
+                        Move to Site…
+                    </button>
                     <div class="dropdown-divider"></div>
                     <button class="dropdown-item text-danger"
                             @onclick="() => DeleteConnection(node.Connection!)">
@@ -409,6 +425,38 @@
         }
     }
 
+    // ── M9-T24b: Move connection to another site ──
+    // The dialog dispatches MoveDataConnectionCommand through the guard-running
+    // ManagementActor path (IDataConnectionMoveService) — NOT a direct repository
+    // write — so the server enforces the Designer gate and every move guard. The
+    // page only opens the dialog, supplies the candidate target sites (the current
+    // site excluded), and reloads the tree once the move succeeds.
+    private bool _showMoveDialog;
+    private int _moveConnectionId;
+    private int _moveConnectionSiteId;
+    private string _moveConnectionName = string.Empty;
+
+    private void OpenMoveDialog(DataConnection conn)
+    {
+        _moveConnectionId = conn.Id;
+        _moveConnectionSiteId = conn.SiteId;
+        _moveConnectionName = conn.Name;
+        _showMoveDialog = true;
+    }
+
+    // Candidate target sites for the move: every site EXCEPT the connection's
+    // current one. Sourced from the already-loaded tree roots (each root is a site).
+    private IEnumerable<(int Id, string Label)> MoveTargetSiteOptions() =>
+        _treeRoots
+            .Where(r => r.SiteId is int sid && sid != _moveConnectionSiteId)
+            .Select(r => (r.SiteId!.Value, r.Label));
+
+    private async Task OnConnectionMoved()
+    {
+        _toast.ShowSuccess($"Connection '{_moveConnectionName}' moved.");
+        await LoadDataAsync();
+    }
+
     // M9-T25: enum → Bootstrap badge class. Mirrors the Health dashboard's
     // GetConnectionHealthBadge (Components/Pages/Monitoring/Health.razor) so the
     // design page surfaces the same colour coding for the same status. Kept as a