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/CLAUDE.md

@@ -0,0 +1,22 @@
+# Effigenix Frontend – Agent Guide
+
+## Stack
+pnpm Workspaces Monorepo, React 18, TypeScript 5, Tailwind v4, Vite 6, tsup, Tauri v2
+
+## Packages
+- `packages/ui` – Shared React Component Library mit Tailwind v4 Theme (Design Tokens)
+- `packages/types` – TypeScript Types (OpenAPI-generiert)
+- `packages/config` – Shared Configuration Constants
+- `packages/validation` – Zod Validation Schemas
+- `packages/api-client` – Type-safe HTTP Client
+
+## Apps
+- `apps/cli` – Terminal UI (Ink + React)
+- `apps/web` – ERP Web-UI (Vite + React + Tailwind v4)
+- `apps/scanner` – Tauri v2 Mobile App (QR-Scanner)
+
+## Dokumentation
+
+### Base UI (Headless Component Library)
+Für komplexere UI-Komponenten (Dialog, Select, Combobox etc.) wird Base UI verwendet.
+AI-optimierte Dokumentation: https://base-ui.com/llms.txt