fix(dev): Vite-API-Proxy, Auth, Stripe-Mails und Backend-Erweiterungen

- Client: API-Basis-URL (joinApiUrl, /v1-Falle), Vite strictPort + Proxy 127.0.0.1, Nicht-JSON-Fehler

- Server: /api-404 ohne Wildcard-Bug, SPA-Fallback, Auth-Middleware, Cron, Mailer, Crypto

- Routen: OAuth-State, Email/Stripe/Analytics; client/.env.example

Made-with: Cursor

server/package.json

@@ -41,7 +41,9 @@
     "googleapis": "^144.0.0",
     "imapflow": "^1.2.8",
     "node-appwrite": "^14.1.0",
-    "stripe": "^17.4.0"
+    "node-cron": "^4.2.1",
+    "nodemailer": "^8.0.4",
+    "stripe": "^17.7.0"
   },
   "devDependencies": {
     "jsdom": "^27.4.0"