fix(ui): propagate schema when creating tabs and new queries

Table/data tabs were missing schema in createTab, so the toolbar
"new query" button couldn't inherit schema from the active tab.
Also add schema to NewQueryTarget so resolveNewQueryTarget
propagates it from both sidebar and active tab contexts.

apps/desktop/src/components/sidebar/TreeItem.vue

@@ -494,7 +494,7 @@ async function openData() {
     table: node.label,
     dbType: config?.db_type,
   });
-  const tabId = queryStore.createTab(node.connectionId, node.database, node.label, "data");
+  const tabId = queryStore.createTab(node.connectionId, node.database, node.label, "data", node.schema);
   console.info("[DBX][openData:tab-created]", { traceId, tabId, elapsed: elapsed() });
   queryStore.setExecuting(tabId, true);