[feat]: Create <pf-v6-description-list> element #2931

Summary

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

Semantic `

` pattern for displaying term/value pairs with layout variants.

Prior Art

Source	Element	Status
PFE v4	--	--
cem	--	--
cockpit	--	--
chickadee	--	--

Requirements

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

Proposed API

<pf-v6-description-list>
  <pf-v6-description-list-group term="Term">
    Description
  </pf-v6-description-list-group>
  <pf-v6-description-list-group>
    <span slot="term">Term 2</span>
    Description
  </pf-v6-description-list-group>
</pf-v6-description-list>

Element-specific considerations

• Must render as native `

  `/`

  `/`

  ` for semantic correctness

• React `isHorizontal` - term and value side-by-side; map to `horizontal` attribute
• React `isAutoColumnWidths` - CSS grid auto column sizing
• React `isAutoFit` - auto-fit grid columns for responsive
• React `isCompact` - reduced spacing
• React `isFluid` - term width grows with content
• React `isFillColumns` - fill CSS grid columns vertically
• React `columnModifier`: `1Col`, `2Col`, `3Col` (+ responsive breakpoint variants) - CSS grid columns
• `DescriptionListTermHelpText` - term with help icon and tooltip; consider slot pattern
• `pf-v6-description-list-group` renders `
  `, `pf-v6-description-list-term` renders `

  `, `pf-v6-description-list-description` renders `

  ` - or slot-based

Checklist

Implementation

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

  `/`

  `/`

  ` structure

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`)