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/SeedSiteSettingsBootstrapper.cs

@@ -46,6 +46,34 @@ public static partial class SeedDataBootstrapper
             settings.WorkflowRulesJson = WorkflowRuleSettings.Serialize(WorkflowRuleSettings.Defaults);
         }
 
+        if (!HasValidTrackingRules(settings.TrackingRulesJson))
+        {
+            settings.TrackingRulesJson = TrackingRulesSettings.Serialize(new TrackingRulesConfiguration(
+                TrackingRulesSettings.DefaultSource,
+                TrackingRulesSettings.DefaultImportantMetrics,
+                TrackingRulesSettings.DefaultOptionalMetrics,
+                TrackingRulesSettings.DefaultFlags));
+        }
+
+        if (string.IsNullOrWhiteSpace(settings.ViewerStatsProviderBaseUrl))
+        {
+            settings.ViewerStatsProviderBaseUrl = TrackingRulesSettings.DefaultBaseUrl;
+        }
+
+        if (string.IsNullOrWhiteSpace(settings.TrackingReviewNotes))
+        {
+            settings.TrackingReviewNotes = """
+Fallback-Quellen für manuelle Reviews:
+- SullyGnome Channel Summary
+- Offizieller Twitch-Kanal
+
+Prüfe bei Edge Cases:
+- passt der Kanal wirklich zur Unterkategorie?
+- fehlen TwitchTracker-Daten nur temporär?
+- braucht der Fall eine manuelle Team-Notiz?
+""";
+        }
+
         if (!HasValidNominationLinkBlacklist(settings.NominationLinkBlacklistJson))
         {
             settings.NominationLinkBlacklistJson = NominationLinkBlacklistSettings.Serialize(NominationLinkBlacklistSettings.Defaults);
@@ -83,7 +111,12 @@ public static partial class SeedDataBootstrapper
 
         if (string.IsNullOrWhiteSpace(settings.ShowactsContent))
         {
-            settings.ShowactsContent = "Informationen zu Showact-Bewerbungen, Ablauf und Kontakt fuer die Award-Show.";
+            settings.ShowactsContent = "Informationen zu Showact-Bewerbungen, Ablauf und Kontakt für die Award-Show.";
+        }
+
+        if (settings.SessionIdleTimeoutHours < 3)
+        {
+            settings.SessionIdleTimeoutHours = 3;
         }
     }
 
@@ -121,6 +154,14 @@ public static partial class SeedDataBootstrapper
     private static bool HasValidWorkflowRules(string? json) =>
         WorkflowRuleSettings.Read(new Backend.Domain.SiteSettings { WorkflowRulesJson = json ?? string.Empty }).Length == WorkflowRuleSettings.Defaults.Length;
 
+    private static bool HasValidTrackingRules(string? json)
+    {
+        var rules = TrackingRulesSettings.Read(new Backend.Domain.SiteSettings { TrackingRulesJson = json ?? string.Empty });
+        return rules.ImportantMetrics.Length == TrackingRulesSettings.DefaultImportantMetrics.Length
+            && rules.OptionalMetrics.Length == TrackingRulesSettings.DefaultOptionalMetrics.Length
+            && rules.Flags.Length == TrackingRulesSettings.DefaultFlags.Length;
+    }
+
     private static bool HasValidNominationLinkBlacklist(string? json)
     {
         if (string.IsNullOrWhiteSpace(json))