Add musings about autostart

# How to auto-start an application?

## Don't boot to X Server / Wayland

I currently want to avoid having to start an X Server or Wayland, mostly because:

* I am afraid they will introduce additional ways to escape my application.

* They will likely add additional complexity I don't need.

This means we will likely even use **Raspberry Pi OS Lite**, because if we don't need an X Server or a desktop environment, why install it?

## Autostart via autologin

1. Create extra user (without `sudo` etc.) for login

2. Configure auto login for that user (there should be official documentation on that)

3. Change shell to the Python app

   * For 2. and 3., see [`autologin.md`](autologin.md) for details

4. Build a terminal-based Python app (e.g. with Textualize)

## Autostart via systemd unit

Currently preferred:

1. Create systemd unit for app, enable it

2. On boot, this will start the app, which will take over the Framebuffer and display its UI