Modify offline mode to include caching on server connection failure

This will likely require a complete refactor of offline mode. We want to now include caching of objects such that if a connection cannot be made to the server, these objects are uploaded at a later time. This can be merged with the offline mode concept, the difference being offline mode would be clearly stating that connection to a server is not possible, whereas a typical run would keep re-trying to upload the runs at a given interval.

This could be merged with the concept of having object orientation for Simvue objects and their storage locally.

未指定文件或测试。首先定位现有的离线模式实现和 Simvue 对象存储路径，然后跟踪 run 的上传方式以及连接失败的处理方式。完成的标准是：连接失败时会缓存对象以便稍后上传，按定义的时间间隔重试，并区分正常重试与明确启用的离线模式。