ts-vikunja/tailscale/config/serve.headscale.json

{
  "TCP": {
    "80": {
      "HTTP": true
    }
  },
  "Web": {
    "vikunja.yourdomain.com:80": {
      "Handlers": {
        "/": {
          "Proxy": "http://127.0.0.1:3456"
        }
      }
    }
  }
}