Feature Request: Support for multi-category axis labels in Column/Bar charts

[cleiton.nunes]

Currently, when creating a chart with hierarchical or multi-level category data, PlanMaker does not visually group the categories on the axis. Having multi-level labels makes it much easier to read nested data structures.
To illustrate, consider this sample dataset containing two levels of categories (Level 1: DD/EE, Level 2: A/B):

DD EE
A B A B
1 4 5 8
2 3 4 7
3 2 3 4

A column/bar chart generated from this data should display a well-organized X-axis, with “A” and “B” shown individually and neatly grouped under their corresponding higher-level categories, “DD” and “EE”, using visual dividers.