* this can be very useful for having a single project that is used for
  both "local" and "containerized" execution, where some configuration
  items should be slightly different for either (e.g. `SEARCH_HOSTS`)
* currently we have this functionality implemented in our `invenio.cfg`
  but there it is a bit awkward due to the fact that environment
  variables have not been translated into `app.config` yet

* this makes sure that our custom translations will be picked up, if we
  ever go for translations

* apparently it was a leftover `before_first_request` handler
* reworked it as `finalize_app` entrypoint
* also, added a check if the app config is already a TUW config to avoid
  unnecessary nesting

* to fix our multi-domain setup with Flask 2.x and 3.0
* see: https://github.com/pallets/flask/pull/5634
* this can be removed once we get Flask 3.1+ in

* create dedicated modules for curations & notifications to separate the
  general notifications infrastructure from the curations-related parts
  (and requests)
* split large modules into smaller logical groups
* split tasks.py into three separate parts: curations, TISS, and general

* to make it more obvious that they are all related to user models
* also, rename the modules to better reflect their content
* also, rename some content (e.g. `CurationForm` to `CurationPreferencesForm`)

* replace the removed `@register_menu` decorator, which was using
  `app.before_first_request` under the hood, with a `finalize_app`
  entrypoint function

* Implements custom TU Wien user identity generator

* use `hatchling` instead of `setuptools` as build tool
* remove `MANIFEST.in` since that's specific to setuptools
* also add `uv.lock` to gitignore