APP_NODE_MODULE_DIRS contains two paths. Quoting that var breaks
the command and the node_module folders were not deleted.

* changed the way how the paths of makefile and .local folder are determined
* removed failsafe and replaced it with quoted path variables

The function `dir`, used to determine MKFILE_DIR can take multiple
parameters. As a result, if this repository is located in a path
that contains a white space, the result of `abspath` is interpreted
as multiple parameters, because Make uses white spaces as separator
or delimiter. Quoting does not help. Spaces as such only work in
shell commands within target bodies.

So, the chosen workaround is to add a failsafe to ask the user for
confirmation to give them a chance to double check what is actually
being deleted.

* added a warning at the top of the readme to raise awareness

* removed hack folder and with it all code to install deps
* reworked `make build` to show more explicitly what needs to be done when
  producing an artifact
* bumped node version dep to v14 (to make jest work again)
* adjusted readme
* suppress console output when running jest client tests

* update server and client package dependencies due to CVE notifications
* update runtime dependencies
* add some information to various readmes (e.g. about the client being part of the bundle)

* adjust app readme
* revert change in server 'scripts'
* renamed 'stack' into 'hack' and split up Makefile into two to better separate
  devops scenarios from scoped deps management
* updated readme according to the make target changes

* update mongoose, jest and nodemon to address security alerts triggered
  by dependabot
* 'test' target had a bug introduced by using wrong syntax
* renamed server scripts to clarify the distinction between invocations
  in local development, CI and actual operations

* npm is a symlink in the node artifact, so, extracting only the symlink
  is no good if its actual target is not there. Now, the whole `node_modules`
  is extracted instead, and a symlink is created explicitly
* remove wildcards to avoid necessity of `--wildcards`, which is not
  supported by BSD tar
* minor phrasing

* adjust mongoose configuration
* documents more make targets in readme
* applied npm scripts convention of the client to the corresponding
  server scripts in order to be more consistent (`start` is now meant
  for local development)

* tech stack can be installed locally and will be used by app-related
  targets if available
* bumped minimal required npm version to 6.14 for server and client

* readme files for the repository and the app
* makefile ans the main entry and documentation
* remove create-react-app from client code