[charts] Show axis tooltip when navigating with keyboard

[Copilot]

When using trigger="axis" tooltip, keyboard navigation did not trigger the tooltip — only pointer interaction did. The item tooltip (trigger="item") already supported keyboard navigation via selectorChartsTooltipItem switching on lastInteraction === 'keyboard', but the axis tooltip selectors had no equivalent path.

Changes

• useChartCartesianTooltip.selectors.ts: Added keyboard-aware branching to selectorChartsInteractionTooltipXAxes and selectorChartsInteractionTooltipYAxes. When lastInteraction === 'keyboard', the selectors now use selectorChartsKeyboardXAxisIndex/selectorChartsKeyboardYAxisIndex to derive the axis data index from the focused item, instead of the pointer position. The triggerTooltip flag is still respected.

• Extracted a shared getKeyboardAxisTooltip helper to avoid duplicating the keyboard branch logic across X and Y selectors.

• contentDisplayed.test.tsx: Added browser test verifying that keyboard navigation (ArrowRight) displays the correct axis tooltip content when trigger="axis" is set.

<BarChart
  series={[...]}
  enableKeyboardNavigation
  slotProps={{ tooltip: { trigger: 'axis' } }}
/>
// Arrow key navigation now shows axis tooltip for the focused data index

This follows the same pattern already used in useChartCartesianHighlight.selectors.ts, which already combined pointer and keyboard axis indices for axis highlight behavior.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[charts] Show axis tooltip when navigating with keyboard</issue_title>
<issue_description>### Summary

When moving focus with keyboard, the tooltip follows the focused item. Similar behavior should be done with tooltip trigger="axis"

Examples

No response

Motivation

No response

Search keywords: a11y, keyboard, tooltip</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [charts] Show axis tooltip when navigating with keyboard #21670

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Details of bundle changes

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