Improve Server Start UX

[JulianVallee]

Is your feature request related to a problem?

When starting the server for the first time, users often encounter confusion due to the black screen resulting from DISABLE_RENDERING=true. This has led to repeated questions on Discord about what to do next.

Describe the feature

Provide clearer guidance to users on what to expect and how to proceed:

• Add a prominent console message explaining the black screen and the purpose of DISABLE_RENDERING.
• Include instructions on how to connect to the server or confirm that the server is running as expected.
• tbd

Additional context

No response

Final checks

• Read the contribution guide.
• Check existing issues.