For people like me who want to double-click all the things

Integrate with the Android "back" button and use it for navigation

Closes #45

See merge request !42

They include some names which need to be adjusted because we moved them
around, unfortunately.

Previous attempts which appeared to work seemed to using our MainWidget.hsc
and reflex-dom's MainWidget.c/h...  These changes seem to convince the build
system to use our copies only.

emacs/haskell-language-server have a harder time with these platform-specific
directories so try to keep things simple and explicit.

and move platform-independent code out of Android module where it is expensive
to build/test.

Hook up the Android back button to the event propagation system.

Handle the Android back button event with browser-based history navigation.

This is aimed at the Android back button for now.  Later it will probably deal
with Android Activity results.  After that, who knows.

reflex-dom does not expose it but we need to use it if we are going to
customize the AndroidActivity - necessary to do things like hook up the back
button or handle activity results from other apps.

Add a tech demo button showing browser history integration

See merge request !41

Make demo data more realistic

See merge request !40

I'm not entirely sure what `performEvent_` is doing here.

Add resources on building UI/UX for Android

Closes #44

See merge request !39

Closes #44.

Add UI for text-based folder invite code entry

Closes #46

See merge request !37

add a job to run cabal build

See merge request !38

we should keep it working for when we eventually add a test suite...

The input is accepted from the magic-folder view when the "+" button is
clicked.  This could be replaced by or augmented with a QR code-scanning
interface later.

Handle the new route in the controller as well, just by rendering the code
into the page as text.

Locally mirror CDN ressources

Closes #28

See merge request !36

(License is the same as for the MDC CSS)

`curl https://unpkg.com/material-components-web@latest/dist/material-components-web.min.js`
-> Found. Redirecting to /material-components-web@14.0.0/dist/material-components-web.min.js

`curl -LO https://unpkg.com/material-components-web@latest/dist/material-components-web.min.js`

`curl -L https://github.com/googlefonts/roboto/raw/main/LICENSE -o roboto`

```
curl 'https://fonts.googleapis.com/css?family=Roboto:300,400,500' -H 'accept: text/css,*/*;q=0.1' -H 'user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36' --compressed -O
grep -oP 'http.*?woff2' roboto.css  | xargs -n 1 curl -O
sed -i 's|https://fonts.gstatic.com/s/roboto/v30/||' roboto.css
```

... after noticing Chrome gets WOFF2 instead of TTF fonts, I
copied the curl commandos with the right user agent strings etc.
directly out of the Chrome Dev Tools network window (right-click
copy as cURL) and downloaded that.

`curl -LO https://github.com/google/material-design-icons/raw/master/LICENSE`

```
curl -LO https://fonts.gstatic.com/s/materialicons/v140/flUhRq6tzZclQEJ-Vdg-IuiaDsNZ.ttf
mv flUhRq6tzZclQEJ-Vdg-IuiaDsNZ.ttf material-icons.ttf
```

curl -LO 'https://fonts.googleapis.com/icon?family=Material+Icons'

Commands used:

Get the version with:
`curl 'https://unpkg.com/material-components-web@latest/dist/material-components-web.min.css'`
-> "Found. Redirecting to /material-components-web@14.0.0/dist/material-components-web.min.css"

Aha so this is version 14.0.0! Download:

`curl -LO 'https://unpkg.com/material-components-web@latest/dist/material-components-web.min.css'`

Add the license:

`curl -LO https://raw.githubusercontent.com/material-components/material-components-web/master/LICENSE`