Let's add a button to minimise (collapse) the sidebar.

When the sidebar is minimised, only link icons (not labels) are visible.

We will also save the sidebar state across requests.

Based on this blogpost:
https://blog.corsego.com/tailwind-collapsible-sidebar

Episode source code:
https://github.com/corsego/138-tailwind-layout/commit/280d649360359de1c346741d130d7cd49c9745d2