KChart v1.18.0 - Tree & Treemap Visualizations

Added

• Added createTreeSeries with orthogonal and radial layouts, four orientations, hierarchy validation, emphasis, click events, tooltips, and pan/zoom support.
• Added Tree Chart demo, StackBlitz project, API documentation, and regression tests.
• Added a Preset-inspired Treemap demo with metric-proportional areas, StackBlitz project, Usage output, and API documentation.

Improved

• Added implementation comments that explain tree hierarchy validation, layout coordinate conversion, cache behavior, and tooltip hit testing.
• Escaped tree tooltip content and documented the treemap binary partition behavior.

Compatibility

• Backward compatible. No migration is required.