Refactor AddedWho assignment in InsertObjectProcedure

AddedWho is now set via the AddedBy method instead of direct assignment in object initializers. The property is made internal with a private setter to prevent external modification. All ToObjectProcedure methods in insert procedure records are updated to use AddedBy for consistency and encapsulation.

src/ReC.Application/Common/Procedures/InsertProcedure/InsertEndpointProcedure.cs

@@ -11,8 +11,7 @@ public record InsertEndpointProcedure : IInsertProcedure
         return new InsertObjectProcedure
         {
             Entity = "ENDPOINT",
-            Endpoint = this,
-            AddedWho = addedWho
-        };
+            Endpoint = this
+        }.AddedBy(addedWho);
     }
 }