[feat]: Create <pf-v6-data-list> element #3005

Summary

Create `` to implement the PatternFly v6 Data list component.

Flexible data rows for displaying structured content without strict column alignment. Supports selectable, expandable, and draggable items.

Prior Art

Sub-components

• `` - Individual row
• `` - Row content container
• `` - Cell group within a row
• `` - Individual cell
• `` - Actions for a row
• `` - Selection checkbox
• `` - Row controls (expand, drag)
• `` - Expandable row toggle
• `` - Expanded row content

Requirements

• MUST implement PFv6 visual designs
• MUST provide end-user feature parity with `@patternfly/react-core` DataList
• MAY adjust element API to leverage web platform strengths
• SHOULD maintain CSS custom property theming compatibility
• SHOULD expose useful CSS shadow parts

Element-specific considerations

• React `isCompact` - reduced row height; map to `compact` attribute
• React `onSelectDataListItem` - fires when a row is clicked; emit `select` event
• React `wrapModifier`: `breakWord`, `nowrap`, `truncate` - text overflow in cells
• Selectable rows: `DataListCheck` renders a checkbox; manage selection in parent
• Expandable rows: `DataListToggle` + `DataListExpandableContent`; `isExpanded` on row
• Draggable: `DataListDragButton`; integrates with `@dnd-kit` or native drag-and-drop
• `DataListAction` with `isPlainButtonAction` vs dropdown for row actions
• ARIA: `role="list"` on container, `role="listitem"` on rows; checkbox pattern for selectable

Checklist

Implementation

• API per `.claude/ADVICE.md`
• CSS uses v6 tokens, logical properties, nesting
• `@summary` and JSDoc on element class

Demos

• Demos match patternfly.org naming/structure
• CSS custom properties match computed styles from patternfly.org (Chrome MCP)
• Visual parity verified via Chrome MCP

Tests

• Public API covered (attributes, properties, events, slots)
• `a11ySnapshot` assertions

Reviews

• `/review-api` passes
• `/review-demos` passes
• `/review-a11y` passes
• `eslint` and `stylelint` pass

Ship

• Add changeset
• PR targets `staging/pfv6` (NOT `main`)