The MessageSystem is based on Subject instead of Content (just semantics)

src/Web/Messages/Handlers/PostReplyMessage.cs

@@ -5,7 +5,7 @@ using Hutopy.Web.Messages.Data;
 namespace Hutopy.Web.Messages.Handlers;
 
 public record PostReplyMessageRequest(
-    Guid ContentId,
+    Guid SubjectId,
     Guid ParentId,
     string Message);
 
@@ -26,7 +26,7 @@ public sealed class PostReplyMessage(
         await context.Messages.AddAsync(
             new Message
             {
-                ContentId = req.ContentId,
+                SubjectId = req.SubjectId,
                 ParentId = req.ParentId,
                 CreatedBy = User.GetUserId(),
                 Value = req.Message