* Add deterministic fixtures and characterization tests for chart data processing
* Extract statistics chart data processing into a pure function
* Extract state history line chart data processing into a pure function
* Add benchmark suite for chart data processing
* Add chart data optimization playbook
* Point agent instructions at the chart optimization playbook
* Render echarts tooltips with Lit templates
Replace raw HTML string interpolation in echarts tooltip formatters with Lit templates so user-controlled fields (entity friendly_name, device names, node labels) are auto-escaped instead of relying on per-string filterXSS. ha-chart-base now wraps any function tooltip.formatter into a stable per-formatter container and handles Lit TemplateResult / nothing / null returns; the public HaECOption type lets charts express Lit-returning formatters without per-callsite casts.
* Simplify
* Refactor _getSeries
* Small fix
* Fix merge mistake
* Marker component and wrapper test
Paul Bottein
Petar Petrov