Description

Currently, the CSV table view supports only a single row of column headers. It would be useful to support multi-level (hierarchical) headers for datasets that have grouped or nested column structures.

Use Case
Some datasets use structured or hierarchical column names, for example:

• Grouped metrics (e.g. “Revenue” → “Q1”, “Q2”, “Q3”, “Q4”)
• Nested data fields (e.g. “User” → “Name”, “Email”, “ID”)

In such cases, a single header row is insufficient to represent the structure clearly.

Proposed Behavior

• Allow defining multiple header rows in the CSV
• Display headers as a hierarchical structure in the table view.
• Optional, but nice to have: Visually group child columns under parent headers (e.g. spanning header cells).