feat(phase-6): event browsing UI — pre-match/live lists, detail page, +26 bUnit tests

Replaces PreMatch/Live placeholder pages with a shared EventListShell
(filter chips, date range, sortable virtualized-friendly table, debounced
search, live auto-refresh with odds-movement indicators) and adds a new
/events/{eventCode} detail page (asymmetric header lockup, dynamic
Match/Period tabs, Plotly.Blazor odds-over-time chart with accessible
data-table fallback, snapshot history, Excel export modal).

New primitives matching Phase 5's editorial-quant system:
- SportIcon: inline SVGs per sport (basketball=6, football=11,
  tennis=22723, hockey=43658, generic fallback)
- OddsCell: tabular mono with ▲/▼/— delta + flash on change
  (prefers-reduced-motion honored)
- OddsTimeline: Plotly.Blazor wrapper with theme-aware colors and
  <details>/<summary> data-table screen-reader fallback
- ExportDialog: From/To pickers + ExportKind radio + Esc/Enter
  keyboard, surfaces use-case errors inline
- EventListShell: shared section shell for PreMatch/Live cadence

State + service split keeps the RCL host-agnostic:
- IEventBrowsingService / EventBrowsingService — wraps repos, returns
  view-model records (EventListItem, EventDetail, EventScopeBoard,
  BetRow, OddsTimelinePoint, SnapshotHistoryEntry); pages never see
  EF or domain entities directly.
- EventBrowsingState — singleton (per-circuit in BlazorWebView) holding
  immutable PageFilter records for PreMatch and Live.

Plotly.Blazor 5.4.1 added (latest .NET 8 line; 7.x has breaking changes).
+59 RU/EN localization keys following the Phase 5 dot-segmented convention.

Tests: +26 bUnit tests (PreMatch/Live/Detail pages, OddsCell/SportIcon/
ExportDialog components, EventBrowsingState). Total 228/228 passing
(Domain 96 + Application 15 + Infrastructure 80 + UI 37; baseline 202).
Build clean (0/0).

PLAN.md: P2/P3/P5 top-level checkboxes ticked; P6 row marked Done.

tests/Marathon.UI.Tests/Pages/PreMatchTests.cs

@@ -0,0 +1,53 @@
+using Bunit;
+using Marathon.UI.Pages;
+using Marathon.UI.Tests.Support;
+
+namespace Marathon.UI.Tests.Pages;
+
+public sealed class PreMatchTests : MarathonTestContext
+{
+    [Fact]
+    public void Renders_seeded_rows()
+    {
+        Browsing.SportCodes.AddRange(new[] { 6, 11 });
+        Browsing.UpcomingItems.AddRange(new[]
+        {
+            TestData.ListItem(id: "EV-1", side1: "Arsenal", side2: "Chelsea"),
+            TestData.ListItem(id: "EV-2", side1: "Lakers", side2: "Bulls", sport: 6),
+        });
+
+        var cut = RenderComponent<PreMatch>();
+        cut.WaitForAssertion(() =>
+        {
+            var rows = cut.FindAll("[data-test=event-row]");
+            rows.Count.Should().Be(2);
+        });
+
+        cut.Markup.Should().Contain("Arsenal");
+        cut.Markup.Should().Contain("Lakers");
+    }
+
+    [Fact]
+    public void Renders_empty_state_when_no_events()
+    {
+        var cut = RenderComponent<PreMatch>();
+        cut.WaitForAssertion(() =>
+        {
+            cut.Markup.Should().Contain("PreMatch.Empty");
+        });
+    }
+
+    [Fact]
+    public void Calls_loader_with_active_filter_dates()
+    {
+        Browsing.UpcomingItems.Add(TestData.ListItem());
+
+        var cut = RenderComponent<PreMatch>();
+        cut.WaitForAssertion(() =>
+        {
+            Browsing.UpcomingCallCount.Should().BeGreaterThan(0);
+            Browsing.LastUpcomingFilter.Should().NotBeNull();
+            Browsing.LastUpcomingFilter!.Dates.From.Should().BeBefore(Browsing.LastUpcomingFilter.Dates.To);
+        });
+    }
+}