test(centralui): fix flaky audit-grid resize-survives-reload test

ResizeHandle_DraggingWidensColumn_AndSurvivesReload called page.ReloadAsync()
immediately after the resize drag, racing the asynchronous persist: pointer-up
fires a fire-and-forget JS→.NET OnColumnResized invoke that round-trips back
through JS interop to write sessionStorage. When the reload won the race the
restored grid fell back to the default column width and the test failed
(~1 in 3 runs).

Wait for auditGrid:columnWidths to land via the existing WaitForStorageKeyAsync
helper before reloading — the same guard the sibling
ColumnOrderAndWidths_PersistAcrossReload_ViaSessionStorage test already uses.
Verified: 6/6 consecutive passes.

tests/ScadaLink.CentralUI.PlaywrightTests/Audit/AuditGridColumnTests.cs

@@ -146,6 +146,14 @@ public class AuditGridColumnTests
             Assert.True(after > before + 40,
                 $"Expected the {columnKey} column to widen after the resize drag (before={before}, after={after}).");
 
+            // The resize persists asynchronously: pointer-up fires a
+            // fire-and-forget JS→.NET OnColumnResized invoke, and the .NET
+            // handler then round-trips back through JS interop to write
+            // sessionStorage. Wait for that write to land before reloading —
+            // otherwise the reload races it and the restored grid falls back
+            // to the default width.
+            await WaitForStorageKeyAsync(page, "auditGrid:columnWidths");
+
             // Reload: the persisted width is restored from sessionStorage.
             await page.ReloadAsync();
             await page.WaitForLoadStateAsync(LoadState.NetworkIdle);