[feat]: Create `<pf-v6-wizard>` element

Start by reading .claude/ADVICE.md and comparing the PatternFly v6 Wizard reference with @patternfly/react-core Wizard behavior. Done means the element and wizard-step support the listed API, demos, accessibility assertions, visual checks, review commands, linting, and changeset requirements.

Summary

Create a <pf-v6-wizard> web component implementing the PatternFly v6 Wizard component.

Multi-step guided workflow with progress sidebar, navigation, and step validation.

Prior Art

Sub-components

• <pf-v6-wizard-step> - Individual step with title and content

Requirements

• MUST implement PFv6 visual designs
• MUST provide end-user feature parity with @patternfly/react-core Wizard
• 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

• Sub-components: WizardHeader, WizardBody, WizardFooter, WizardNav, WizardNavItem, WizardStep, WizardToggle (mobile)
• Step props: id, name, isDisabled, isVisited, sub-steps (nested WizardNavItem)
• onNext, onBack, onClose, onNavItemClick events
• isNavItemsExpanded for sub-step nav expand/collapse
• Current step tracked internally; startIndex for initial step
• Footer: Back / Next / Cancel buttons with per-step override via WizardFooterWrapper
• Mobile: collapsible nav via WizardToggle
• Nav landmark: <nav aria-label="Wizard steps">, current step aria-current="page"
• Consider wrapping in <dialog> for modal wizard variant (use showModal())
• Step content area: role="main" or aria-labelledby pointing to step title

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)