Various issues when setting up development environment

As discussed in a recent PR, here are some issues, minor and major, as well as a few suggestions on how to resolve those. Will happily contribute with improved documentation if we can agree on the best way forward.

1. First off, I just tried to run the client, not minding the server stuff. However, without proper server setup, the steps in `/app/README.md` led to "A JavaScript error occurred in the main process", specifically "spawn poetry ENOENT", though it still kind of runs. _Fair enough, the server is required to run the client application, but perhaps this should be documented in /app/README.md then?_

1. In `pyproject.toml`, versions `python = "^3.8, !=3.9.0, <3.11"` are specified. However, upon running 3.10 locally, I ran into this issue:

> ERROR: Could not build wheels for numpy, which is required to install pyproject.toml-based projects

I'm not a python dev by trade, but a quick search indicates that this is due to 3.10 being "too new"? _Either way, 3.8 works fine, and since you specify 3.8 in `release.yml` anyway, I don't see why not just enforce the same version in `pyproject.toml` for simplicity._

3. In `/server/README.md`, you state:

> You need to download a model for speech recognition into the `../data/` directory

This is slightly ambiguous and raises questions, namely:
- Does `../data` mean it is a sibling directory to `app` and `server`?
- If yes, I would expect to either find the directory already present, or to find it `.gitignore`d, none of which is the case(?)
- Finally, you suggest the alternative: "or by running the `download_models.sh` script" but this script doesn't exist(?)

4. Lastly (for now), the console spits out a few errors, some more alarming than others:
- "RuntimeWarning: Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work" (this sounds like something a developer should have set up in their environment in advance? Can't find it documented)
- ExtensionLoadWarning: Warnings loading extension at C:\Users\joel.garplind\AppData\Roaming\Electron\extensions\lmhkpmbekcpmknklioeibfkpmmfibljd:
Unrecognized manifest key 'commands'.
Unrecognized manifest key 'homepage_url'.
Unrecognized manifest key 'page_action'.
Unrecognized manifest key 'short_name'.
Unrecognized manifest key 'update_url'.
Permission 'notifications' is unknown or URL pattern is malformed.
Permission 'contextMenus' is unknown or URL pattern is malformed.
Cannot load extension with file or directory name \_metadata. Filenames starting with "\_" are reserved for use by the system.
- ExtensionLoadWarning: Warnings loading extension at C:\Users\joel.garplind\AppData\Roaming\Electron\extensions\fmkadmapgofadopljbjfkapdkoienihi:
Unrecognized manifest key 'browser_action'.
Unrecognized manifest key 'minimum_chrome_version'.
Unrecognized manifest key 'update_url'.
Cannot load extension with file or directory name \_metadata. Filenames starting with "\_" are reserved for use by the system.

I don't care much about the last two, except that they make me as a first-time contributor feel insecure whether my environment is set up properly.