feat(chart): add links to data point tooltips

[lovasoa]

Summary

Closes #945.

Adds an optional row-level link parameter to the chart component. When a chart data row has a link, the chart tooltip includes an accessible Open link anchor pointing to that URL.

Implementation

• Carries link through the chart template's point data without changing the existing color/z positions.
• Preserves links on aligned series points.
• Uses a small DOM-based tooltip renderer only for charts that contain links; charts without links keep ApexCharts' existing tooltip behavior.
• Handles range bars and other point-based charts, including pie-series data stored by ApexCharts as scalar values.
• Documents the parameter and adds a timeline example.

Tests

• npm test
• cargo test
• cd tests/end-to-end && npm run test -- --grep "data point link"

[lovasoa]

Thank you very much, @81reap ! Switching this back to draft while we iterate

[lovasoa]

Visual verification after the accessible tooltip-link styling update:

[81reap]

sorry, I didn't realize this was still in draft. happy to do code reviews whenever tho!