Charting
Use chart placeholders in your HTML; the system renders charts server-side to images to ensure PDF reliability.
Usage
<div class="chart-placeholder" data-chart='{ "type": "bar", "data": { /*...*/ } }'></div>
At preview and generation time, placeholders are replaced with <img alt=\"Chart\" src=\"data:image/...\" />.
Related: docs/chart-positioning-controls.md