feat(centralui): open ExecutionDetailModal on tree-node double-click

src/ScadaLink.CentralUI/Components/Pages/Audit/ExecutionTreePage.razor

@@ -52,7 +52,14 @@
                 View this execution in the Audit Log
             </a>
         </div>
-        <ExecutionTree Nodes="_nodes" ArrivedFromExecutionId="_executionId.Value" />
+        <ExecutionTree Nodes="_nodes" ArrivedFromExecutionId="_executionId.Value"
+                       OnNodeActivated="HandleNodeActivated" />
+
+        @* Double-clicking a tree node raises OnNodeActivated, which opens this
+           modal for that execution. The modal renders nothing while IsOpen is
+           false, so it is safe to place unconditionally here. *@
+        <ExecutionDetailModal ExecutionId="_modalExecutionId" IsOpen="_modalOpen"
+                              OnClose="HandleModalClose" />
     }
     else
     {

src/ScadaLink.CentralUI/Components/Pages/Audit/ExecutionTreePage.razor.cs

@@ -40,6 +40,15 @@ public partial class ExecutionTreePage
     private bool _loading;
     private string? _error;
 
+    // Execution-Tree Node Detail Modal feature (Task 4) — state backing the
+    // <ExecutionDetailModal>. A double-click on a tree node sets
+    // _modalExecutionId + flips _modalOpen true; the modal loads that
+    // execution's audit rows on the closed → open transition. _modalOpen is the
+    // visibility gate — _modalExecutionId is left intact across a close (it is
+    // harmless while the modal is hidden and avoids a flicker if reopened).
+    private Guid? _modalExecutionId;
+    private bool _modalOpen;
+
     protected override async Task OnInitializedAsync()
     {
         _executionId = ParseExecutionId();
@@ -90,4 +99,22 @@ public partial class ExecutionTreePage
             _loading = false;
         }
     }
+
+    /// <summary>
+    /// Raised by <c>ExecutionTree</c> (bubbled up from a node double-click) with
+    /// the activated node's <c>ExecutionId</c>. Opens the
+    /// <c>ExecutionDetailModal</c> for that execution — the modal loads its
+    /// audit rows on the closed → open transition.
+    /// </summary>
+    private void HandleNodeActivated(Guid executionId)
+    {
+        _modalExecutionId = executionId;
+        _modalOpen = true;
+    }
+
+    /// <summary>
+    /// Raised by <c>ExecutionDetailModal</c> when the user dismisses it. Flips
+    /// the visibility gate closed; <see cref="_modalExecutionId"/> is left as-is.
+    /// </summary>
+    private void HandleModalClose() => _modalOpen = false;
 }