chore: initial scaffold (Whitelabel-Fork von Pfandsystem)

- Source-Copy von /root/entwicklung/pfandsystem
- docker-compose.yml umgeschrieben: pfandsystem-demo-* Container, Ports 3308/8083/3003 (alle localhost)
- Traefik-Label fuer pfandsystem.dockly.de
- Erweitertes Multi-Tenant-Schema (tenants, tenant_id auf allen Tabellen)
- Neue Tabellen: kunden_bilder, geraete
- Neue Spalten: kunden.anlieferungshinweis, kunden.lieferzeit_bis
- Rollen: superadmin, admin, user, fahrer
- .env.example + README

Code-Refactor (Tailwind, Multi-Tenant-Middleware, Erweiterungen) folgt.

backend/middleware/auth.js

@@ -0,0 +1,32 @@
+import jwt from 'jsonwebtoken';
+
+export const authenticateToken = (req, res, next) => {
+  const authHeader = req.headers['authorization'];
+  const token = authHeader && authHeader.split(' ')[1]; // Bearer TOKEN
+
+  if (!token) {
+    return res.status(401).json({ error: 'Kein Token bereitgestellt' });
+  }
+
+  jwt.verify(token, process.env.JWT_SECRET, (err, user) => {
+    if (err) {
+      return res.status(403).json({ error: 'Ungültiger oder abgelaufener Token' });
+    }
+    req.user = user;
+    next();
+  });
+};
+
+export const requireRole = (roles) => {
+  return (req, res, next) => {
+    if (!req.user) {
+      return res.status(401).json({ error: 'Nicht authentifiziert' });
+    }
+    
+    if (!roles.includes(req.user.rolle)) {
+      return res.status(403).json({ error: 'Keine Berechtigung' });
+    }
+    
+    next();
+  };
+};

backend/middleware/upload.js

@@ -0,0 +1,46 @@
+import multer from 'multer';
+import path from 'path';
+import { fileURLToPath } from 'url';
+import fs from 'fs';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+// Upload-Verzeichnis erstellen, falls nicht vorhanden
+const uploadDir = process.env.UPLOAD_DIR || path.join(__dirname, '../uploads');
+if (!fs.existsSync(uploadDir)) {
+  fs.mkdirSync(uploadDir, { recursive: true });
+}
+
+// Multer-Konfiguration
+const storage = multer.diskStorage({
+  destination: (req, file, cb) => {
+    cb(null, uploadDir);
+  },
+  filename: (req, file, cb) => {
+    const uniqueSuffix = Date.now() + '-' + Math.round(Math.random() * 1E9);
+    const ext = path.extname(file.originalname);
+    cb(null, `foto-${uniqueSuffix}${ext}`);
+  }
+});
+
+const fileFilter = (req, file, cb) => {
+  // Nur Bilder erlauben
+  const allowedTypes = /jpeg|jpg|png|gif|webp/;
+  const extname = allowedTypes.test(path.extname(file.originalname).toLowerCase());
+  const mimetype = allowedTypes.test(file.mimetype);
+
+  if (mimetype && extname) {
+    return cb(null, true);
+  } else {
+    cb(new Error('Nur Bilddateien sind erlaubt (JPEG, PNG, GIF, WebP)'));
+  }
+};
+
+export const upload = multer({
+  storage: storage,
+  limits: {
+    fileSize: parseInt(process.env.MAX_FILE_SIZE) || 10 * 1024 * 1024 // 10MB default
+  },
+  fileFilter: fileFilter
+});