fix: remove unnecessary JSON.stringify for appended parameter in message handling

supabase/functions/create-chat-conversation/index.ts

@@ -343,7 +343,7 @@ app.post(`${prefix}/conversations/:id/messages`, async (c) => {
       "append_conversacion_plan",
       {
         p_id: conversation_plan_id,
-        p_append: JSON.stringify(appended),
+        p_append: appended,
       },
     );
 
@@ -402,7 +402,7 @@ app.post(`${prefix}/conversations/:id/messages`, async (c) => {
       "append_conversacion_plan",
       {
         p_id: conversation_plan_id,
-        p_append: JSON.stringify(appended),
+        p_append: appended,
       },
     );