Final polish, functional audit, and new Vue components ...

- Fix interactive overlay pointer-events for modal/drawer
- Add accordion panel transition so animation completes
- Fix toast inline handler syntax escaping
- Install real Phosphor Icons fonts and CSS
- Add auto-init for browser helpers and GNexusUIKit alias
- Add functional Playwright tests for all interactive components
- Add new Vue components: GnIconButton, GnInputGroup, GnDescriptionList, GnEmptyState, GnPageHeader
- Update kit.scss with new component styles
- All 17 e2e tests, Vue adapter smoke, and production build passing

Co-Authored-By: Claude <noreply@anthropic.com>