Fix sync: CreateList action + server ID mapping

- Added SyncAction::CreateList variant
- create_task returns server Task, added create_list API
- Sync engine processes CreateList first, updates IDs in batch
- After Create/CreateList success, local IDs updated to server IDs

src/app.rs

@@ -473,7 +473,7 @@ impl App {
                         };
                         self.db.insert_list(&list).ok();
                         self.db.push_sync(
-                            SyncAction::Create,
+                            SyncAction::CreateList,
                             &list.id,
                             &list.id,
                             &serde_json::to_string(&list).unwrap_or_default(),