feat: migrate frontend to Astro SSG with design system

- Replace monolithic React SPA (App.tsx) with 7 Astro pages (+ routing)
- Implement full design system from design/ (OKLCH tokens, Tailwind 4 @theme)
- Add 12 Astro components (Button, Badge, Card, Sidebar, Header, states)
- Add 11 React islands (AuthGuard, MessageFeed, VoiceControls, AudioVisualizer, etc.)
- Add 3 Zustand stores (UI, voice, message state)
- Add CSS architecture: dark/light themes, glassmorphism, fluid typography, animations
- Add 404, login, settings, recordings pages
- Remove 40+ legacy React SPA files
- Add Particles background and MascotChat deferred islands
- Wire WebSocket bridge for real-time messages and voice events

Build: 7 pages in ~900ms
Typecheck: clean (0 errors)
Lint: clean (0 errors)

services/frontend/package.json

@@ -23,7 +23,8 @@
     "lucide-react": "^1.16.0",
     "react": "^19.2.6",
     "react-dom": "^19.2.6",
-    "tailwind-merge": "^3.6.0"
+    "tailwind-merge": "^3.6.0",
+    "zustand": "^5.0.14"
   },
   "devDependencies": {
     "@biomejs/biome": "latest",