Frontend design overhaul: Warm Plum & Gold theme

- Typography: Replace Inter with Bricolage Grotesque (display) + DM Sans (body)
- Colors: New palette with plum primary, rose secondary, gold accent
- Animations: Staggered entrance animations for cards and stats
- Background: Gradient mesh atmosphere with subtle noise texture
- Celebrations: Confetti on purchase, pulse/glow effects on claims
- Dark mode: Updated to match new warm color palette

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ssk42