feat(design): bioluminescent green+violet palette and re-tuned landing hero

feat(theme): dual light/dark mode with Apple light theme, toggle, and theme-aware viewers

Refine design system: semantic color tokens, tiered motion, denser result cards, VinaLog toolbar

Convert legacy light pages (auth, callback, shared, blast) and components to native dark tokens

refactor(icons): migrate lucide-react to @phosphor-icons/react, remove dep

chore: frontend design polish (accent palette, remove glow/gradient utils), ignore installed skill trees, add opencode skills config

fix: add missing /api prefix to audit fetch URLs so rewrite proxy reaches backend router at /api/audit/event

feat: 4-layer audit/observability system