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.

plans/initial-implementation/CONTEXT.md

@@ -85,7 +85,7 @@ with scraping research, no implementation.
 | Phase 3 | phase-implementer | Sonnet 4.6 | ⏭️ Skipped (Big Bang) | ✅ With 2 + 5 | — |
 | Phase 4 | phase-implementer | Sonnet 4.6 | ⏭️ Skipped (Big Bang) | — | ✅ Done 2026-05-05. 4 use cases, 3 BackgroundService pollers, InfrastructureModule, ApplicationModule, reflection wiring removed. 202/202 tests green (+17 new). |
 | Phase 5 | phase-implementer-frontend | Opus | ⏭️ Skipped (Big Bang) | ✅ With 2 + 3 | Uses frontend-design skill |
-| Phase 6 | phase-implementer-frontend | Opus | ⏭️ Skipped (Big Bang) | — | Uses frontend-design skill |
+| Phase 6 | phase-implementer-frontend | Opus | ⏭️ Skipped (Big Bang) | — | ✅ Done 2026-05-05. PreMatch + Live + Events/Detail pages, EventListShell, SportIcon, OddsCell, OddsTimeline (Plotly.Blazor wrap), ExportDialog. EventBrowsingState + IEventBrowsingService facade. RU+EN strings under PreMatch.* / Live.* / Detail.* / Export.* / Sport.*. 228/228 tests green (+26 new bUnit). |
 | Phase 7 | phase-implementer (split if needed) | Sonnet/Opus | ⏭️ Skipped (Big Bang) | — | UI portion uses Opus |
 | Phase 8 | phase-implementer (split if needed) | Sonnet/Opus | ⏭️ Skipped (Big Bang) | — | UI portion uses Opus |
 | Phase 9 | phase-implementer | Sonnet 4.6 | ✅ Final phase tests | — | Full build + test enforced |
@@ -101,6 +101,49 @@ with scraping research, no implementation.
 
 ## Implementation Notes
 
+### Phase 6 (Event browsing UI, 2026-05-05)
+
+- **Plotly.Blazor pinned to 5.4.1.** v7.x exists but introduces breaking changes;
+  5.4.1 is the latest on the .NET 8 line and works with our existing MudBlazor
+  7.15.0 / .NET 8.0.12 stack. The `Plotly.Blazor.LayoutLib.Margin` type clashes
+  with `MudBlazor.Margin` — fully qualify the layout-side type.
+- **Razor source generator does NOT accept C# 11 raw string literals (`"""…"""`)**
+  inside `@code` blocks. The parser sees the leading `"""` as the start of a
+  normal string and never finds the close, producing an "Unterminated string
+  literal" RZ1000. Use concatenated single-quoted attribute strings instead
+  (see `SportIcon.razor` SVG constants).
+- **Razor reserves the identifier `code`.** A `@foreach (var code in ...)`
+  loop is parsed as the `@code` directive, not as iteration. Use any other
+  identifier (`var sportCode in ...`).
+- **`MudBlazor.DateRange` shadows `Marathon.Application.Storage.DateRange`**
+  in any file whose `_Imports.razor` brings both namespaces in. Add
+  `using AppDateRange = Marathon.Application.Storage.DateRange;` per-file
+  where the application's `DateRange` is constructed (already done in
+  `ExportDialog.razor` and `ExportDialogTests.cs`).
+- **EventBrowsingService is Scoped, EventBrowsingState is Singleton.** The
+  service captures the per-circuit DI scope so EF Core's `DbContext` lifetime
+  works correctly; the state object holds the per-page filter records and
+  fires `OnChange` only when the new value !equals the old one. This split
+  matches Phase 5's split between `ThemeState` (singleton) and per-circuit
+  data services.
+- **View-models, not domain entities, cross the UI boundary.** Pages bind to
+  `EventListItem` / `EventDetail` / `BetRow` / `OddsTimelinePoint`
+  records (defined in `Marathon.UI.Services`). Repositories are not exposed
+  to Razor components. This keeps the UI free of EF tracked graphs and
+  preserves Phase 5's "RCL is host-agnostic" invariant.
+- **Live page reads polling cadence from `IOptionsMonitor<ScrapingSettingsForm>`.**
+  Phase 4's `WorkerOptions.LivePollIntervalSeconds` (drives the poller) is a
+  separate setting from the UI's display refresh; the latter intentionally
+  follows `Scraping:PollingIntervalSeconds` per the Phase 6 subplan.
+- **Plotly chart memoization.** Computed signature = `(count, first ticks,
+  last ticks, first/last rate triples)`. Sufficient to invalidate the trace
+  list on any meaningful change while staying cheap during live polling.
+- **bUnit shared `MarathonTestContext` now registers the fake browsing service
+  and the browsing state.** Phase 7 tests can extend it directly or follow the same pattern.
+  `Support/TestData.MoscowToday(int hour)` produces correctly-offset
+  `DateTimeOffset` values — domain `Event.ScheduledAt` will reject any other
+  offset.
+
 ### Phase 1 (Solution skeleton + Domain model, 2026-05-05)
 
 - **.NET 10 SDK creates `.slnx` by default.** `dotnet new sln` produces `Marathon.slnx`