Feature Request: Expose groupBy configuration in public API

Problem:

BasesQueryResult.groupedData provides pre-grouped data, but the public API doesn’t expose which property was used for grouping. Custom views that allow users to modify group membership need this information to update the correct frontmatter property.

Proposed Solution:

Add to BasesViewConfig:

/**
 * Get the property ID used for grouping in this view.
 * Returns null if no groupBy is configured.
 * @public
 */
getGroupBy(): BasesPropertyId | null;

Current Workaround:

controller.query.views.find(v => v.name === viewName)?.groupBy?.property

This relies on undocumented internal API and may break in future updates.