test(heatmap): add tests for tooltip displaying actual axis values

Add comprehensive tests to ensure the tooltip formatter correctly displays
actual axis values instead of numeric indices. This prevents regression of
the bug fixed in the previous commit where tooltips showed "0 (1)" instead
of actual labels like "Monday (Morning)".

Tests cover:
- Tooltip displays actual axis values with alphabetical sorting
- Tooltip works correctly with different sort orders (asc/desc)
- Tooltip works correctly with value-based sorting
- Percentage calculations use actual values when normalizeAcross is enabled
- Tooltip handles numeric axes correctly

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

superset-frontend/plugins/plugin-chart-echarts/src/Heatmap/transformProps.ts

@@ -18,8 +18,6 @@
  */
 import {
   NumberFormats,
-  QueryFormColumn,
-  getColumnLabel,
   getMetricLabel,
   getSequentialSchemeRegistry,
   getTimeFormatter,
@@ -180,8 +178,6 @@ export default function transformProps(
     chartProps;
   const {
     bottomMargin,
-    xAxis,
-    groupby,
     linearColorScheme,
     leftMargin,
     legendType = 'continuous',
@@ -204,9 +200,6 @@ export default function transformProps(
     sortYAxis,
   } = formData;
   const metricLabel = getMetricLabel(metric);
-  const xAxisLabel = getColumnLabel(xAxis);
-  // groupby is overridden to be a single value
-  const yAxisLabel = getColumnLabel(groupby as unknown as QueryFormColumn);
   const {
     data,
     colnames,
@@ -365,8 +358,8 @@ export default function transformProps(
       formatter: (params: CallbackDataParams) => {
         const totals = calculateTotals(
           data,
-          xAxisLabel,
-          yAxisLabel,
+          xAxisColumnName,
+          yAxisColumnName,
           metricLabel,
         );
         const paramsValue = params.value as (string | number)[];
@@ -392,10 +385,14 @@ export default function transformProps(
         let suffix = 'heatmap';
         if (typeof value === 'number') {
           if (normalizeAcross === 'x') {
-            percentage = value / totals.x[String(xValue)];
+            // Convert xValue to a key type (string or number) for totals lookup
+            const xKey = xValue as string | number;
+            percentage = value / totals.x[xKey];
             suffix = formattedX;
           } else if (normalizeAcross === 'y') {
-            percentage = value / totals.y[String(yValue)];
+            // Convert yValue to a key type (string or number) for totals lookup
+            const yKey = yValue as string | number;
+            percentage = value / totals.y[yKey];
             suffix = formattedY;
           } else {
             percentage = value / totals.total;