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/Endpoints/AdminSeasonCategoryEndpoints.cs

@@ -46,6 +46,8 @@ public static partial class AdminSeasonManagementEndpoints
             Description = request.Description.Trim(),
             SortOrder = request.SortOrder,
             MaxNomineesPerUser = request.MaxNomineesPerUser,
+            ViewerRangeMin = request.ViewerRangeMin,
+            ViewerRangeMax = request.ViewerRangeMax,
         };
 
         db.Categories.Add(category);
@@ -97,6 +99,8 @@ public static partial class AdminSeasonManagementEndpoints
         category.Description = request.Description.Trim();
         category.SortOrder = request.SortOrder;
         category.MaxNomineesPerUser = request.MaxNomineesPerUser;
+        category.ViewerRangeMin = request.ViewerRangeMin;
+        category.ViewerRangeMax = request.ViewerRangeMax;
 
         adminAuditService.AddEntry(
             session.TwitchUserId,