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/Data/SeedData.cs

@@ -49,15 +49,23 @@ Keine Weitergabe zu Werbezwecken. Technische Dienstleister verarbeiten Daten aus
                 SponsorsUrl = "https://vtuber-star-awards.de/partner",
                 SponsorsContent = SeedCatalog.DefaultSponsorsContent,
                 ShowactsUrl = "https://vtuber-star-awards.de/showacts",
-                ShowactsContent = "Informationen zu Showact-Bewerbungen, Ablauf und Kontakt fuer die Award-Show.",
+                ShowactsContent = "Informationen zu Showact-Bewerbungen, Ablauf und Kontakt für die Award-Show.",
                 RiskRulesJson = RiskRuleSettings.Serialize(RiskRuleSettings.Defaults),
                 WorkflowRulesJson = WorkflowRuleSettings.Serialize(WorkflowRuleSettings.Defaults),
+                TrackingRulesJson = TrackingRulesSettings.Serialize(new TrackingRulesConfiguration(
+                    TrackingRulesSettings.DefaultSource,
+                    TrackingRulesSettings.DefaultImportantMetrics,
+                    TrackingRulesSettings.DefaultOptionalMetrics,
+                    TrackingRulesSettings.DefaultFlags)),
+                ViewerStatsProviderBaseUrl = TrackingRulesSettings.DefaultBaseUrl,
+                TrackingReviewNotes = "Fallback-Quellen für manuelle Reviews:\\n- SullyGnome\\n- Twitch-Kanal direkt\\n\\nNutze diese Notizen für Edge Cases und manuelle Tier-Entscheidungen.",
                 NominationLinkBlacklistJson = NominationLinkBlacklistSettings.Serialize(NominationLinkBlacklistSettings.Defaults),
                 ClipSubmissionsEnabled = false,
                 ClipReviewEnabled = true,
                 ClipSubmissionDisabledMessage = "Clip-Einreichungen sind aktuell geschlossen.",
                 ShowactApplicationsEnabled = false,
                 ShowactApplicationDisabledMessage = "Showact-Bewerbungen sind aktuell geschlossen.",
+                SessionIdleTimeoutHours = 3,
                 SponsorsVisible = true,
                 SocialLinksJson = JsonSerializer.Serialize(new[]
                 {
@@ -152,7 +160,7 @@ Keine Weitergabe zu Werbezwecken. Technische Dienstleister verarbeiten Daten aus
             });
 
         modelBuilder.Entity<Category>().HasData(
-            new Category { Id = 1, SeasonId = 1, GroupName = "Main Awards", Name = "VTuber des Jahres", Slug = "vtuber-des-jahres", Description = "Die groesste Auszeichnung des Jahres.", SortOrder = 1, MaxNomineesPerUser = 3 },
+            new Category { Id = 1, SeasonId = 1, GroupName = "Main Awards", Name = "VTuber des Jahres", Slug = "vtuber-des-jahres", Description = "Die größte Auszeichnung des Jahres.", SortOrder = 1, MaxNomineesPerUser = 3 },
             new Category { Id = 2, SeasonId = 1, GroupName = "Performance", Name = "Bestes Live Event", Slug = "bestes-live-event", Description = "Events, Konzerte und 3D-Shows.", SortOrder = 2, MaxNomineesPerUser = 3 },
             new Category { Id = 3, SeasonId = 1, GroupName = "Clips & Highlights", Name = "Clip des Jahres", Slug = "clip-des-jahres", Description = "Der lustigste oder emotionalste Clip des Jahres.", SortOrder = 3, MaxNomineesPerUser = 3 },
             new Category { Id = 4, SeasonId = 1, GroupName = "Main Awards", Name = "Beste Community", Slug = "beste-community", Description = "Die aktivste und freundlichste Community.", SortOrder = 4, MaxNomineesPerUser = 3 },