add indication in the browser and cli that circuit is currently loading

[Anshgrover23]

/claim #29
Fixes #29

Reference video:

2025-02-02.18-54-08.mov

[ShiboSoftwareDev]

The issue is not for a loading screen, When the server refreshes and the circuit is still rendering you should indicate to the user that the circuit is rendering, because currently there is no feedback

[ShiboSoftwareDev]

@Anshgrover23
something like this:

or this:

[seveibar]

no SSE, you should propose an approach in the issue, the whole reason we have a standard file server is because the server was getting too custom and complicated in the old CLI. The server must remain incredibly simple with just and event bus and api for updating files.

If we're in the process of rendering, you could simply emit an event CIRCUIT_RENDERING_STARTED and CIRCUIT_RENDERING_FAILED or CIRCUIT_RENDERING_FINISHED (then subscribe to these in the browser)