style(adminui): group UNS page + modal buttons into btn-groups

Task 3 of the AdminUI UI sweep. Behavior-preserving markup only:

- GlobalUns: Expand/Collapse pair -> btn-group btn-group-sm (Import stays
  separate); delete-confirm footer Cancel+Delete -> btn-group.
- Area/Line/ScriptedAlarm/VirtualTag/AddReference/ImportEquipment modal
  footers: Cancel + primary -> btn-group.
- EquipmentPage: the three text-end action cells (Save name/Remove,
  Edit/Delete x2) -> btn-group btn-group-sm, me-1 spacers dropped.
- UnsTree: per-node actions become real small buttons (outline-secondary,
  outline-danger for destructive) and adjacent runs of >=2 group into
  btn-group btn-group-sm; the genuine navigation links (cluster settings,
  equipment Open) stay links. Expander/leaf placeholder adopt .tree-twist
  in place of the inline width:18px.

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Uns/ScriptedAlarmModal.razor

@@ -99,11 +99,13 @@
                         }
                     </div>
                     <div class="modal-footer">
-                        <button type="button" class="btn btn-outline-secondary" @onclick="CancelAsync" disabled="@_busy">Cancel</button>
-                        <button type="submit" class="btn btn-primary" disabled="@_busy">
-                            @if (_busy) { <span class="spinner-border spinner-border-sm me-1"></span> }
-                            @(IsNew ? "Create" : "Save changes")
-                        </button>
+                        <div class="btn-group" role="group">
+                            <button type="button" class="btn btn-outline-secondary" @onclick="CancelAsync" disabled="@_busy">Cancel</button>
+                            <button type="submit" class="btn btn-primary" disabled="@_busy">
+                                @if (_busy) { <span class="spinner-border spinner-border-sm me-1"></span> }
+                                @(IsNew ? "Create" : "Save changes")
+                            </button>
+                        </div>
                     </div>
                 </EditForm>
             </div>