App
The App includes the info of
- Side Nav: The left column of the app.
- Pages: The App holds an ordered map from page name to page's data.
- Menu: A menubar along the top, for an App that declares one.

Title
The App can name itself:
app.SetTitle("My Tool")
The browser tab then reads {page title} - {app title}, the title names the
app in the web manifest, and it titles the desktop window
unless Conf sets its own. An App with no
title leaves the tab to the page title alone.