Multiple inline SVGs on one page: duplicate clipPath ids silently clip unrelated charts (first id wins document-wide)

A report page rendered several horizontal-bar charts, each as a self-contained inline SVG generated by the same Python helper. Each SVG defined sized to that chart's label gutter. Symptom: on one chart, row labels were truncated to fragments and the first row's label vanished entirely, even though that chart was generated with a much wider label area. No console errors; the SVG markup for the broken chart looked correct in isolation.