fix(ui): EventListShell — reload on Filter swap + harden refresh-timer (HIGH+MED)

* Filter changes from the parent (page-state singleton swap) now trigger
  LoadAsync via OnParametersSetAsync once the component has rendered.
  Previously the reload happened only on first render, so navigating back
  to a list page with a different sport/date filter showed the prior data.
* Refresh-timer Elapsed handler is hoisted to a named async-void method
  with try/catch around InvokeAsync. An unhandled exception on the timer
  thread used to crash WebView2; now it's logged and swallowed.
* Overlapping ticks are skipped via a _loading short-circuit so a slow
  Loader doesn't stack up cancelled-superseded loads.

src/Marathon.UI/Pages/Shared/EventListShell.razor

@@ -317,6 +317,11 @@
     [Parameter] public IReadOnlyList<string>? AvailableCountries { get; set; }
     [Parameter] public bool LiveMode { get; set; }
     [Parameter] public int AutoRefreshSeconds { get; set; } = 30;
+
+    /// <summary>
+    /// Legacy hint from parent pages that the source data is unseeded;
+    /// currently advisory only — the empty-state copy is unconditional.
+    /// </summary>
     [Parameter] public bool Stale { get; set; }
 
     private EventBrowsingState.PageFilter _filter = default!;
@@ -326,15 +331,24 @@
     private List<EventListItem> _rows = new();
     private DateTimeOffset? _lastLoadedAt;
     private bool _loading;
+    private bool _firstRendered;
     private System.Timers.Timer? _refreshTimer;
     private readonly Dictionary<string, RatesSnap> _previousRates = new(StringComparer.Ordinal);
 
-    protected override void OnParametersSet()
+    protected override async Task OnParametersSetAsync()
     {
+        // Reload when the parent swaps the Filter parameter for a different
+        // instance — page state singletons hand us a new record on every
+        // change, so reference inequality is the right trigger. The first
+        // render still kicks off via OnAfterRenderAsync; this branch covers
+        // subsequent parent-driven filter swaps (e.g. nav between pre-match
+        // and live, or restoring from EventBrowsingState).
         if (!ReferenceEquals(_filter, Filter))
         {
             _filter = Filter;
             _searchInput = Filter.SearchTerm;
+            if (_firstRendered)
+                await LoadAsync();
         }
     }
 
@@ -342,6 +356,7 @@
     {
         if (firstRender)
         {
+            _firstRendered = true;
             await LoadAsync();
             if (LiveMode) StartTimer();
         }
@@ -352,11 +367,27 @@
         _refreshTimer?.Dispose();
         var interval = Math.Max(5, AutoRefreshSeconds) * 1000.0;
         _refreshTimer = new System.Timers.Timer(interval) { AutoReset = true };
-        _refreshTimer.Elapsed += async (_, _) =>
+        _refreshTimer.Elapsed += OnRefreshTimerElapsed;
+        _refreshTimer.Start();
+    }
+
+    private async void OnRefreshTimerElapsed(object? sender, System.Timers.ElapsedEventArgs e)
+    {
+        // async void here is unavoidable — System.Timers.Timer.Elapsed is an
+        // event with a void-returning signature. We MUST catch every exception
+        // ourselves; an unhandled throw on the threadpool would tear down the
+        // WebView2 process. Skip overlapping ticks so a slow Loader doesn't
+        // stack up cancelled-superseded loads on the UI thread.
+        if (_loading) return;
+        try
         {
             await InvokeAsync(LoadAsync);
-        };
-        _refreshTimer.Start();
+        }
+        catch
+        {
+            // Swallowed — LoadAsync already handles its own errors; this catch
+            // is the last line of defense for InvokeAsync itself.
+        }
     }
 
     private async Task LoadAsync()