SSR Sessions 🔥
Sessions with timeout for SSR

```nim
serve "127.0.0.1", 5000:
  var globalSessionId = ""
  "/":
    var session = startSession(10)  # timeout in seconds
    globalSessionId  = session.id
    return session.id
  "/closeGlobalSession":
    closeSession(globalSessionId)
    return "closed, try to return to '/'"
```