refactor: hoist Moscow offset + sport labels into shared helpers (HIGH)

* New Marathon.Domain.ValueObjects.MoscowTime with Offset, Now, and
  EndOfMoscowDay(DateOnly) — replaces ~15 inline TimeSpan.FromHours(3)
  literals across Domain/Application/Infrastructure/UI.
* New Marathon.UI.Services.SportLabels.Resolve(IStringLocalizer, int) —
  replaces 6 near-identical SportLabel switch bodies in EventListShell,
  Events/Detail, Anomalies/AnomalyFeed, Results/ResultsList,
  Results/ResultsLoader, and AnomalyCard. Single source of truth for the
  6/11/22723/43658 sport-code mapping. Pages keep a one-liner wrapper so
  the call sites stay terse.

src/Marathon.UI/Pages/Anomalies/AnomalyFeed.razor

@@ -252,8 +252,7 @@
     {
         if (DateTimeOffset.TryParse(e.Value?.ToString(), out var v))
         {
-            var moscow = TimeSpan.FromHours(3);
-            await UpdateFilter(_filter with { From = new DateTimeOffset(v.Date, moscow) });
+            await UpdateFilter(_filter with { From = new DateTimeOffset(v.Date, MoscowTime.Offset) });
         }
     }
 
@@ -261,8 +260,7 @@
     {
         if (DateTimeOffset.TryParse(e.Value?.ToString(), out var v))
         {
-            var moscow = TimeSpan.FromHours(3);
-            await UpdateFilter(_filter with { To = new DateTimeOffset(v.Date, moscow).AddDays(1).AddSeconds(-1) });
+            await UpdateFilter(_filter with { To = MoscowTime.EndOfMoscowDay(DateOnly.FromDateTime(v.Date)) });
         }
     }
 
@@ -283,14 +281,7 @@
         _                      => L["Anomaly.Severity.Low"],
     };
 
-    private string SportLabel(int code) => code switch
-    {
-        6      => L["Sport.Basketball"],
-        11     => L["Sport.Football"],
-        22723  => L["Sport.Tennis"],
-        43658  => L["Sport.Hockey"],
-        _      => string.Format(System.Globalization.CultureInfo.InvariantCulture, "Sport {0}", code),
-    };
+    private string SportLabel(int code) => SportLabels.Resolve(L, code);
 
     private static string FormatDate(DateTimeOffset? value)
         => value?.ToString("yyyy-MM-dd") ?? string.Empty;