Polish visual defects: color cards, spacing, date picker, file attachments, progress, input group, timeline, icon mappings ...

- demo: remove page background layer, add vertical spacing for demo rows
- palette: wrap color swatches in color cards with name/hex labels
- description list: style description-list-term distinctly
- file-upload: shrink attachment cards to 130px, increase gaps, center placeholder text
- forms: add .input-date styling with calendar icon and focus ring
- input-group: seamless action slot button without double borders
- progress: add vertical spacing between consecutive progress bars
- timeline: align marker connector line at left: 23px
- vue: make GnIconButton label optional, add Phosphor icon mappings
- tests: screenshot workflow passing, all 19 e2e tests green

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

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>