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/PublicSeasonCategoryReadEndpoints.cs

@@ -1,6 +1,7 @@
 using Backend.Contracts;
 using Backend.Data;
 using Backend.Common;
+using Backend.Services;
 using Microsoft.EntityFrameworkCore;
 
 namespace Backend.Endpoints;
@@ -21,7 +22,9 @@ public static partial class PublicEndpoints
         }
 
         var phaseKey = SeasonMappings.NormalizePhaseKey(season.CurrentPhase);
+        var subcategoryTemplates = SeasonSubcategoryTemplateSettings.Read(season, season.Categories);
         var publicCategories = season.Categories
+            .Where(category => SeasonSubcategoryTemplateSettings.MatchesTemplate(category, subcategoryTemplates))
             .Where(category => ShouldExposePublicCategory(phaseKey, category.Candidates.Count))
             .ToArray();
         var publicCategoryIds = publicCategories.Select(category => category.Id).ToArray();
@@ -54,6 +57,8 @@ public static partial class PublicEndpoints
                 category.GroupName,
                 category.Description,
                 category.MaxNomineesPerUser,
+                category.ViewerRangeMin,
+                category.ViewerRangeMax,
                 category.Candidates
                     .Where(candidate => !string.Equals(candidate.AcceptanceStatus, "declined", StringComparison.OrdinalIgnoreCase))
                     .Select(candidate =>