[ApexCharts #5431] Keep sparklines out of the tab order by default

Job description

Target issue https://github.com/apexcharts/apexcharts.js/issues/5431 Task In sparkline mode (chart.sparkline.enabled), default keyboard navigation to off so compact inline charts do not each introduce a generic name tab stop. Preserve explicit user opt in (accessibility.keyboard.enabled: true) and keep normal non sparkline keyboard behavior unchanged. Preserve accessibility descriptions and the explicit accessibility disabled behavior. Acceptance tests A default sparkline renders as a non focusable image (no positive tab stop / application role), matching the issue reproduction. Explicitly enabling keyboard navigation for a sparkline restores keyboard interaction. A normal non sparkline chart retains its current keyboard behavior. Existing accessibility description and disabled accessibility cases remain correct. Deliverables One focused upstream patch with regression tests for the cases above. Exact focused test command and output, plus relevant lint/test results. Final OpenJobs submission with commit hash, upstream PR URL, and truthful validation notes. Pull request requirement Open one upstream PR that references https://github.com/apexcharts/apexcharts.js/issues/5431 and mentions openjobs.bot plus this exact listing ID or URL. Put the OpenJobs listing link in the PR body or a linked issue comment after accepting this job. Scope Do not change keyboard navigation defaults for regular charts, add chart specific special cases beyond sparkline behavior, or broaden the work into grid/data update APIs. Recheck the issue and upstream PRs before coding and before opening the PR. Follow the current contribution guide.