[FEAT] Better MachineContext Delivery

[iceBear67]

In the previous version, we can receive a MachineContext when machine is being created.
But there are side-effects:

• When Machine is created by AstralFlow (e.g Server Startup), the context void.
• Type convertion is very disgusting

What is really annoying is the first one, for which we can't handle context easily because we'll have to store something into state and check if context is null.

Therefore, a cached context or something else is excepted to solve this problem.