Add calendar integrations and collaboration updates

backend/src/Socialize.Api/Modules/ContentItems/Data/ContentItemActivityEntry.cs

@@ -0,0 +1,16 @@
+namespace Socialize.Api.Modules.ContentItems.Data;
+
+public class ContentItemActivityEntry
+{
+    public Guid Id { get; set; }
+    public Guid WorkspaceId { get; set; }
+    public Guid ContentItemId { get; set; }
+    public required string EventType { get; set; }
+    public required string EntityType { get; set; }
+    public Guid EntityId { get; set; }
+    public required string Summary { get; set; }
+    public Guid? ActorUserId { get; set; }
+    public string? ActorEmail { get; set; }
+    public string? MetadataJson { get; set; }
+    public DateTimeOffset CreatedAt { get; set; }
+}