[feat]: Update `<pf-v6-helper-text>` for PatternFly v6

Summary

Update `` to implement the PatternFly v6 Helper text component.

Contextual help or validation messages displayed beneath form fields, with status variants (default, success, warning, error).

Prior Art

Source	Element	Status
PFE v4	``	Exists
cem	--	--
cockpit	--	--
chickadee	``	Similar

Sub-components

• `` - Individual helper text message with optional icon

Requirements

• MUST implement PFv6 visual designs
• MUST provide end-user feature parity with `@patternfly/react-core` HelperText
• 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 `component`: `div` or `ul` - drives whether items render as `
• `; may not need attribute if slot handles it semantically
• React `isLiveRegion` - adds `aria-live="polite"` and `aria-atomic`; map to `live` attribute
• `HelperTextItem` props: `variant` (`default`, `indeterminate`, `warning`, `success`, `error`), `hasIcon`, `isDynamic`, `icon` (custom icon)
• `isDynamic` on item - item is dynamically shown/hidden (live region relevance); verify v6 behavior
• Items with `error` variant should set appropriate `aria-live` or be associated via `aria-describedby` on the field
• Consider whether `` needs to be a separate custom element or a slotted pattern

Checklist

Rename

• Delete `elements/pf-v5-helper-text/`
• Update `elements/package.json` exports
• Update `eslint.config.js` ignore globs if applicable
• Update docs `_snippets/` and `framework-integration/` references

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`)