[docs]: Request Lifecycle Doc

[LadyBluenotes]

Description

Doc to explicitly cover the full lifecycle of a request, walking through everything that can happen from start to finish.

Something like:

• where it enters (the entry point, if server.ts exists)
• where it goes next (global request middleware)
• the custom render handler
• server routes
• server route middleware
• and how the server routes (and their middleware) end up delegating to SSR

[LadyBluenotes]

@schiller-manuel can you assign me pls / add any other info you want me to include