feat: Update dashboard to match design system (#16)

feat: Update dashboard to match design system (#16)

* feat: Update dashboard to match design system

- Apply design system tokens (colors, typography, radius, shadows)
- Add branded "Redaction Bar Loader" animation for loading/empty states
- Add favicon route serving inline SVG
- Update README with wordmark SVG and optimized screenshot
- Move assets to assets/ folder (logo, wordmark, favicon, dashboard)

* fix: Formatting and browser compatibility fixes

- Fix biome formatting in favicon route (multi-line object)
- Add color-mix() fallback for card hover effect (older browsers)