feat(frontend): Tauri Apps, Shared UI Library und Nix Flake

- packages/ui: Shared React Component Library (Button, Card, Badge, Input)
  mit Tailwind v4 @theme Design Tokens (oklch)
- apps/web: ERP Web-UI (Vite + React + Tailwind v4, API-Proxy :8080)
- apps/scanner: Tauri v2 Mobile App mit Barcode-Scanner Plugin
  (cfg(mobile) für Desktop-Kompatibilität)
- flake.nix: Nix Flake mit rust-overlay, Tauri System-Deps (GTK,
  WebKitGTK, libsoup, OpenSSL), ersetzt shell.nix
- justfile: Dev-Befehle für alle Projekte (backend, cli, web, scanner)
- frontend/CLAUDE.md: Agent Guide mit Base UI Docs Referenz

frontend/apps/web/package.json

@@ -0,0 +1,31 @@
+{
+  "name": "@effigenix/web",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Effigenix ERP Web UI",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc -b && vite build",
+    "preview": "vite preview",
+    "typecheck": "tsc --noEmit"
+  },
+  "dependencies": {
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0",
+    "@effigenix/ui": "workspace:*",
+    "@effigenix/api-client": "workspace:*",
+    "@effigenix/types": "workspace:*",
+    "@effigenix/validation": "workspace:*",
+    "@effigenix/config": "workspace:*"
+  },
+  "devDependencies": {
+    "@types/react": "^18.2.48",
+    "@types/react-dom": "^18.2.18",
+    "@vitejs/plugin-react": "^4.2.1",
+    "@tailwindcss/vite": "^4.0.0",
+    "tailwindcss": "^4.0.0",
+    "typescript": "^5.3.3",
+    "vite": "^6.0.0"
+  }
+}