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

Summary

Update `` to implement the PatternFly v6 Progress component.

Progress bar indicating completion percentage, with optional label, description, and status variants.

Prior Art

Requirements

• MUST implement PFv6 visual designs
• MUST provide end-user feature parity with `@patternfly/react-core` Progress
• 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 `value`, `min` (default 0), `max` (default 100)
• React `measureLocation`: `outside`, `inside`, `none` - controls label position
• React `status`: `success`, `warning`, `danger`, `info` - drives icon and color
• React `size`: `sm`, `lg` (default md)
• React `title` - visible label above bar; `aria-label` fallback when no title
• React `helperText` - text below bar (maps to `` or slot)
• React `truncate` on title - CSS only
• ARIA: `role="progressbar"`, `aria-valuenow`, `aria-valuemin`, `aria-valuemax`, `aria-label`/`aria-labelledby`

Checklist

Rename

• Delete `elements/pf-v5-progress/`
• 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`)