chore(viz): remove legacy explore_json + viz.py pipeline (#41714)

Co-authored-by: Claude Code <noreply@anthropic.com>

superset-frontend/plugins/plugin-chart-echarts/src/TimePivot/buildQuery.ts

@@ -0,0 +1,34 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+import { buildQueryContext, QueryFormData } from '@superset-ui/core';
+
+/**
+ * Mirrors the legacy NVD3TimePivotViz.query_obj: a timeseries query with
+ * the single metric.
+ */
+export default function buildQuery(formData: QueryFormData) {
+  const { metric } = formData;
+  return buildQueryContext(formData, baseQueryObject => [
+    {
+      ...baseQueryObject,
+      is_timeseries: true,
+      metrics: metric ? [metric] : [],
+    },
+  ]);
+}