feat: enforce tenant isolation and shared question bank

Tiku.Application/Content/ContentManagementModels.cs

@@ -1,6 +1,7 @@
 using System.Text.Json;
 using Tiku.Application.Catalog;
 using Tiku.Domain.Content;
+using Tiku.Application.QuestionBanks;
 
 namespace Tiku.Application.Content;
 
@@ -79,7 +80,7 @@ public sealed record ReplaceCollectionItemsCommand(
     IReadOnlyCollection<CollectionQuestionCommand> Questions);
 
 public sealed record CollectionQuestionCommand(
-    Guid QuestionId,
+    QuestionLocator Locator,
     string? SectionKey,
     int? Order,
     decimal? Score,
@@ -173,6 +174,7 @@ public sealed record QuestionCollectionItemManagementItem(
     Guid Id,
     Guid CollectionId,
     Guid QuestionId,
+    QuestionLocator Locator,
     string? SectionKey,
     int Order,
     decimal? Score,