Add cellPosition and onCellPositionChange props

[severo]

This gives the parent component a way to control cell navigation:

const [cellPosition, setCellPosition] = useState<CellPosition>({rowIndex: 1, colIndex: 1})

return <HighTable cellPosition={cellPosition} onCellPositionChange={setCellPosition} data={data} />

Screencast.From.2026-02-05.22-43-10.mp4

This replaces #396.

I'll not add tests for now, because we already have tests for the internal logic, and the stories work well.
But, mostly, because we cannot test the scroll with jsdom. See #423.

[Copilot]

Pull request overview

This PR adds controlled component support for cell navigation by introducing cellPosition and onCellPositionChange props to the HighTable component. This replaces the previous PR #396's approach of using custom event targets, providing a more idiomatic React pattern for parent components to control which cell is active.

Changes:

• Adds cellPosition and onCellPositionChange props following the controlled/uncontrolled component pattern
• Integrates these props into CellNavigationProvider using the existing useInputState hook
• Updates documentation to clearly explain controlled vs uncontrolled modes and lifecycle expectations

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/types.ts	Adds CellPosition prop definitions with comprehensive documentation for controlled/uncontrolled modes
src/providers/CellNavigationProvider.tsx	Integrates cellPosition props with useInputState hook; updates focus state handling
src/components/HighTable/HighTable.tsx	Threads cellPosition and onCellPositionChange props through to CellNavigationProvider
src/providers/ScrollProvider.tsx	Removes outdated parameter documentation comment
src/helpers/scroll.ts	Removes completed TODO comment
src/components/HighTable/HighTable.stories.tsx	Adds JumpToCell story demonstrating controlled cell navigation with buttons

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[Copilot]

The button label says "column 4" but the code sets colIndex: 2. The colIndex should be 4 to match the label, or the label should say "column 2" to match the code.

Suggested change

	<button type="button" onClick={() => { setCellPosition({ rowIndex: 100_000_000, colIndex: 2 }) }}>
	<button type="button" onClick={() => { setCellPosition({ rowIndex: 100_000_000, colIndex: 4 }) }}>

[Copilot]

The comment "focus is broken" suggests there is a known issue with the feature being demonstrated in this story. This should either be fixed before merging, or if it's a temporary comment for development purposes, it should be removed. If it's a known limitation, it should be documented more clearly explaining what specifically is broken and why.

Suggested change

	{/* focus is broken */}
	{/* Note: changing cellPosition scrolls to the target cell but does not move browser keyboard focus. */}

[Copilot]

The commented out code should either be removed or have a clear explanation of why it's kept. Dead code that's commented out makes the codebase harder to maintain. If different data sources are needed for testing, consider using Storybook controls or multiple story variants instead.

Suggested change

// data: createUnsortableData(),

[platypii]

tested locally, looks good!