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/packages/ui/package.json

@@ -0,0 +1,60 @@
+{
+  "name": "@effigenix/ui",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Shared React component library with Tailwind v4 theme",
+  "type": "module",
+  "exports": {
+    ".": {
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.js"
+      }
+    },
+    "./theme.css": "./src/theme.css"
+  },
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "files": [
+    "dist",
+    "src/theme.css"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "dev": "tsup --watch",
+    "typecheck": "tsc --noEmit",
+    "clean": "rm -rf dist"
+  },
+  "peerDependencies": {
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0"
+  },
+  "devDependencies": {
+    "@types/react": "^18.2.48",
+    "@types/react-dom": "^18.2.18",
+    "clsx": "^2.1.1",
+    "tailwind-merge": "^2.6.0",
+    "tsup": "^8.0.1",
+    "typescript": "^5.3.3"
+  },
+  "dependencies": {
+    "clsx": "^2.1.1",
+    "tailwind-merge": "^2.6.0"
+  },
+  "tsup": {
+    "entry": [
+      "src/index.ts"
+    ],
+    "format": [
+      "esm"
+    ],
+    "dts": true,
+    "clean": true,
+    "sourcemap": true,
+    "splitting": false,
+    "external": [
+      "react",
+      "react-dom"
+    ]
+  }
+}