Add viewer-range categories, nomination tracking, dynamic showact form, session timeout, share URLs, and workflow-per-season

Features:
- Category viewer ranges + subcategory templates (admin group modal, tree workspace)
- Nomination enrichment via TwitchTracker API (NominationEnrichmentService,
  TwitchTrackerViewerStatsProvider) with admin tracking rules editor
- Nomination group tracker: CategoryGroupName as primary identifier,
  CategoryId stays as nullable legacy field; StreamerIdentity table
- Dynamic showact application form builder (AdminShowactFormBuilder,
  ShowactApplicationSchedule)
- Session idle timeout setting (AdminSessionTimeoutCard)
- Share URLs for X and Discord (SiteSettings, public extras)
- Workflow rules now stored per season (falls back to global SiteSettings)
- New admin routes: settings/access, settings/workflows, tracking-rules
- New admin review workspace with subcategory tabs
- AdminCategoriesView rebuilt with group/subcategory modals

Migrations (all additive):
- AddShareUrls, AddShowactDynamicForm, AddCategoryViewerRanges,
  AddSessionIdleTimeoutSettings, AddSeasonSubcategoryTemplates,
  AddNominationGroupTrackerIdentity, AddShowactApplicationSchedule,
  AddSeasonWorkflowRulesJson

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Backend/Contracts/AdminModerationContracts.cs

@@ -55,11 +55,27 @@ public sealed record AdminAuditEntriesResponse(
 
 public sealed record AdminNominationReviewItemDto(
     int Id,
-    int CategoryId,
+    int? CategoryId,
+    string CategoryGroupName,
     string CategoryName,
     string SubmittedByTwitchId,
     string CandidateText,
     string? StreamUrl,
+    string? ResolvedChannel,
+    string? ResolvedPlatform,
+    int? AvgViewers,
+    int? SuggestedCategoryId,
+    string? SuggestedCategoryName,
+    int? StreamerIdentityId,
+    string TrackerStatus,
+    DateTimeOffset? TrackerCheckedAt,
+    string TrackingReviewStatus,
+    bool RequiresManualReview,
+    AdminTrackingFlagHitDto[] TrackingFlags,
+    AdminTrackingMetricStateDto[] TrackingMetrics,
+    string? TrackingReviewNote,
+    string? TrackingReviewedByTwitchId,
+    DateTimeOffset? TrackingReviewedAt,
     string Status,
     DateTimeOffset CreatedAt,
     int? CandidateId,
@@ -68,6 +84,32 @@ public sealed record AdminNominationReviewItemDto(
     string? ReviewedByTwitchId,
     DateTimeOffset? ReviewedAt);
 
+public sealed record AdminNominationReviewGroupDto(
+    int Id,
+    int[] NominationIds,
+    string CategoryGroupName,
+    string DisplayName,
+    string? StreamUrl,
+    string? ResolvedChannel,
+    string? ResolvedPlatform,
+    int? AvgViewers,
+    int? SuggestedCategoryId,
+    string? SuggestedCategoryName,
+    int? StreamerIdentityId,
+    string TrackerStatus,
+    DateTimeOffset? TrackerCheckedAt,
+    string TrackingReviewStatus,
+    bool RequiresManualReview,
+    AdminTrackingFlagHitDto[] TrackingFlags,
+    AdminTrackingMetricStateDto[] TrackingMetrics,
+    string? TrackingReviewNote,
+    string? TrackingReviewedByTwitchId,
+    DateTimeOffset? TrackingReviewedAt,
+    int NominationTally,
+    int UniqueSubmitterCount,
+    DateTimeOffset FirstSubmittedAt,
+    DateTimeOffset LastSubmittedAt);
+
 public sealed record AdminClipSubmissionItemDto(
     int Id,
     int? CategoryId,
@@ -87,10 +129,17 @@ public sealed record ApproveNominationRequest(
     string? DisplayName,
     string? ChannelSlug,
     string? Platform,
+    int? CategoryId,
     string? ReviewNote);
 
 public sealed record RejectNominationRequest(string? ReviewNote);
 
+public sealed record ReopenRejectedNominationRequest(string? ReviewNote);
+
+public sealed record UpdateNominationTrackingReviewRequest(
+    string Status,
+    string? ReviewNote);
+
 public sealed record AdminNominationLinkBlacklistEntryDto(string Url);
 
 public sealed record AdminNominationLinkBlacklistResponse(AdminNominationLinkBlacklistEntryDto[] Entries);
@@ -136,3 +185,24 @@ public sealed record AdminWorkflowRuleDto(
 public sealed record AdminWorkflowRulesResponse(AdminWorkflowRuleDto[] Rules);
 
 public sealed record UpdateWorkflowRulesRequest(AdminWorkflowRuleDto[] Rules);
+
+public sealed record AdminTrackingFlagHitDto(
+    string Key,
+    string Label,
+    string Severity,
+    string Description,
+    bool RequiresManualReview,
+    bool BlocksApproval,
+    bool AdminNoteRequiredOnOverride);
+
+public sealed record AdminTrackingMetricStateDto(
+    string Key,
+    string Label,
+    bool Required,
+    string SourceSupport,
+    bool Present,
+    string Value,
+    string Description,
+    string WindowKey,
+    string WindowLabel,
+    bool AutoWindowSupported);