fix(central-ui): resolve CentralUI-007..014 — nav authz, UTC date filters, disposal guards, N+1 fix, async script analysis

src/ScadaLink.CentralUI/Components/Shared/DiffDialog.razor

@@ -150,6 +150,11 @@
 
     public async ValueTask DisposeAsync()
     {
+        // CentralUI-011: if the dialog is disposed while still open (the user
+        // navigated away), complete the pending task so the awaiting caller
+        // resumes deterministically instead of hanging forever.
+        _tcs?.TrySetResult(false);
+
         if (_bodyLocked)
         {
             await TryUnlockBodyAsync();