A heatmap colours a grid of correlations. Build that grid yourself from a small table that mixes text and number columns.
Task: write correlation_grid(rows). rows is a list of dictionaries, one per record, and every dictionary has the same keys.
Return a dictionary with two keys:
"columns": the names of the number columns, in the order they appear in the first record"grid": the correlation between every pair of those columns, as a list of rows (one list per column, in the same order), each value rounded to 2 decimal placesSkip every text column. There are no missing values, there are at least two number columns, and no number column holds the same value in every row.