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/AdminSeasonContracts.cs

@@ -16,14 +16,25 @@ public sealed record AdminCategoryItemDto(
     string Description,
     int SortOrder,
     int MaxNomineesPerUser,
+    int? ViewerRangeMin,
+    int? ViewerRangeMax,
     int CandidateCount);
 
+public sealed record AdminSubcategoryTemplateDto(
+    string Name,
+    string Slug,
+    int SortOrder,
+    int? ViewerRangeMin,
+    int? ViewerRangeMax);
+
 public sealed record AdminCandidateItemDto(
     int Id,
     int CategoryId,
+    int? StreamerIdentityId,
     string DisplayName,
     string ChannelSlug,
     string Platform,
+    int NominationTally,
     string AcceptanceStatus,
     string? AcceptanceNote,
     string? ClipCompilationUrl,
@@ -36,6 +47,7 @@ public sealed record AdminAwardResultItemDto(
     int CategoryId,
     string CategoryName,
     int CandidateId,
+    int? StreamerIdentityId,
     string CandidateDisplayName,
     string CandidateChannelSlug,
     string CandidatePlatform);
@@ -56,10 +68,14 @@ public sealed record AdminSeasonDetailResponse(
     DateOnly ReviewEndsAt,
     DateOnly ShowDate,
     TimeOnly ShowStartsAt,
+    IEnumerable<AdminSubcategoryTemplateDto> SubcategoryTemplates,
     IEnumerable<AdminCategoryItemDto> Categories,
     IEnumerable<AdminCandidateItemDto> Candidates,
     IEnumerable<AdminNominationReviewItemDto> PendingNominations,
+    IEnumerable<AdminNominationReviewGroupDto> PendingNominationGroups,
     IEnumerable<AdminNominationReviewItemDto> ReviewedNominations,
+    string TrackingReviewNotes,
+    bool ShowTrackingReviewNotes,
     IEnumerable<AdminAwardResultItemDto> Results,
     IEnumerable<AdminClipSubmissionItemDto> ClipSubmissions);
 
@@ -102,6 +118,17 @@ public sealed record UpsertCategoryRequest(
     string Slug,
     string Description,
     int SortOrder,
+    int MaxNomineesPerUser,
+    int? ViewerRangeMin,
+    int? ViewerRangeMax);
+
+public sealed record UpdateSeasonSubcategoryTemplatesRequest(
+    AdminSubcategoryTemplateDto[] Templates);
+
+public sealed record UpsertCategoryGroupRequest(
+    string GroupName,
+    string Description,
+    int SortOrder,
     int MaxNomineesPerUser);
 
 public sealed record UpsertCandidateRequest(