feat: migrate Leptos frontend to Next.js 16 (React 19)

Complete migration from services/frontend.old/ (Leptos 0.7 WASM + Rust)
to services/frontend/ (Next.js 16 static export + TypeScript + Tailwind v4).

Summary:
- Port all shared types (message, guild, voice, media, dashboard, recording, ui)
- Build fetch-based API client covering all 30+ backend endpoints
- WebSocket client with auto-reconnect (exponential backoff, 20 attempts)
- React context provider for WS with typed event subscription (22 event types)
- Login page with localStorage auth + auto-redirect
- Dashboard layout with sidebar, header (WS status + theme toggle)
- Messages: feed, search, images tab, review tab, channel filter, detail modal
- Live: voice connection, music player, recordings, mic transmit, active speakers
- Dashboard: stats, user list, channel list, detail views
- Mascot chatbot with history + clear
- uiStateApi persistence for selected tab
- Add static export config, update deploy scripts and CI

services/frontend/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "frontend",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "lint": "biome check",
+    "format": "biome format --write"
+  },
+  "dependencies": {
+    "@base-ui/react": "^1.6.0",
+    "class-variance-authority": "^0.7.1",
+    "clsx": "^2.1.1",
+    "lucide-react": "^1.27.0",
+    "next": "16.2.12",
+    "react": "19.2.4",
+    "react-dom": "19.2.4",
+    "shadcn": "^4.15.0",
+    "tailwind-merge": "^3.6.0",
+    "tw-animate-css": "^1.4.0"
+  },
+  "devDependencies": {
+    "@biomejs/biome": "2.2.0",
+    "@tailwindcss/postcss": "^4",
+    "@types/node": "^20",
+    "@types/react": "^19",
+    "@types/react-dom": "^19",
+    "babel-plugin-react-compiler": "1.0.0",
+    "tailwindcss": "^4",
+    "typescript": "^5"
+  },
+  "ignoreScripts": [
+    "sharp",
+    "unrs-resolver"
+  ],
+  "trustedDependencies": [
+    "sharp",
+    "unrs-resolver"
+  ]
+}