feat(ui): AuditResultsGrid + AuditLogQueryService with keyset paging (#23 M7)

Adds the results grid + query facade for the central Audit Log page
(#23 M7-T3):

* IAuditLogQueryService / AuditLogQueryService — CentralUI facade over
  IAuditLogRepository.QueryAsync so the grid can be tested with a stubbed
  query source. Default page size is 100; callers can override per call.

* AuditResultsGrid.razor + .razor.cs — Blazor Server component (Bootstrap
  only, no third-party UI libs). Renders the 10 columns from
  Component-AuditLog.md §10 (OccurredAtUtc, Site, Channel, Kind, Status,
  Target, Actor, DurationMs, HttpStatus, ErrorMessage). Keyset-paged via
  the last visible row's (OccurredAtUtc, EventId) as the cursor; Next-page
  button disabled when the current page is short (no count query). Row
  clicks emit OnRowSelected(AuditEvent) for Bundle C's drilldown drawer.
  Status badges are colour-coded (Delivered=green; Failed/Parked/Discarded
  =red; other=gray). Error messages truncated to 80 chars with full text
  on hover.

* Column model framework: a ColumnOrder [Parameter] reorders columns by
  stable string keys; unknown keys are dropped. M7 scope decision (in the
  class doc): the framework is in place but drag-reorder / resize UX is
  not implemented — M7.x can add persisted-per-user reordering without
  rewriting the column model.

* AuditLogPage wired: hosts AuditFilterBar + AuditResultsGrid, threads
  the filter through and stubs OnRowSelected for Bundle C.

* AuditLogQueryService registered as scoped in AddCentralUI.

* Tests: 4 grid bUnit tests (10 columns rendered, next-page cursor
  carries last row, row click raises callback, badge classes for
  Failed vs Delivered), 2 service tests (filter+paging pass-through,
  default page size of 100). AuditLogPageScaffoldTests updated to
  provide the new ISiteRepository + IAuditLogQueryService stubs the
  page now resolves.

src/ScadaLink.CentralUI/Components/Pages/Audit/AuditLogPage.razor.cs

@@ -1,12 +1,32 @@
+using ScadaLink.Commons.Entities.Audit;
+using ScadaLink.Commons.Types.Audit;
+
 namespace ScadaLink.CentralUI.Components.Pages.Audit;
 
 /// <summary>
-/// Code-behind for the central Audit Log page (#23 M7-T1). The Bundle A
-/// scaffold has no behaviour — the filter bar and results grid arrive in
-/// Bundle B (M7-T2..M7-T7). Keeping the partial class in place now lets
-/// later bundles add injected services and event handlers without
-/// touching the route or page-title markup.
+/// Code-behind for the central Audit Log page (#23 M7). Bundle B (M7-T2 + M7-T3)
+/// wires up <c>AuditFilterBar</c> and <c>AuditResultsGrid</c>: the page owns the
+/// active <see cref="AuditLogQueryFilter"/> and re-pushes a fresh instance to the
+/// grid on every Apply (the grid uses reference identity as its "reload"
+/// trigger). Row clicks land in <see cref="HandleRowSelected"/> — Bundle C wires
+/// this to the drilldown drawer; for now it is a no-op seam so test stubs do
+/// not error.
 /// </summary>
 public partial class AuditLogPage
 {
+    private AuditLogQueryFilter? _currentFilter;
+
+    private void HandleFilterChanged(AuditLogQueryFilter filter)
+    {
+        // Always reassign — the grid keys reloads on reference change, so even a
+        // chip-for-chip identical filter must allocate a fresh instance.
+        _currentFilter = filter;
+    }
+
+    private void HandleRowSelected(AuditEvent row)
+    {
+        // Reserved for Bundle C (drilldown drawer). Intentionally left empty: the
+        // grid still raises the event, but we do nothing with it yet.
+        _ = row;
+    }
 }