Improve integration/deployment of web front-end

Currently, the web front end is in the `www` directory. It has to be deployed separately from the Spotbit server.

We would like this web front-end to be served from Spotbit servers `/`. That is:

## Done in #79
- [x] Move the code and assets in `www` to the `templates` and `static` directories.
- [x] Rewrite `server.py: @app.get('/')` to serve the front-end.

## TODO
- [ ] Remove the `www` directory.
- [ ] Update the code that parses Spotbit responses (use Typescript where possible).
- [templates/index.html](https://github.com/BlockchainCommons/spotbit/blob/c62901bf9591b89575548fb22e23e9814720791a/www/index.html#L568) uses a `proxy.php` endpoint. This should instead use the new Spotbit endpoints (whose documentation can be found at the `/docs` endpoint of a running Spotbit instance).
- [ ] Update `installSpotbit.sh` or add documentation that describes how to host the front-end in clearnet using Apache or some other reverse proxy e.g. [Caddy](https://caddyserver.com/). (see )