For the first version lets return random questions. API should return latest unfinished test or create a new one.

Would be nice to have code coverage check, which would not allow the quality of the tests to degrade on the later phases.
Let's integrate with https://codecov.io/ and add a badge to the README :)

When I try to connect to the server using the frontend app, I get:

Access to fetch at 'http://localhost:8080/vocabulary' from origin 'http://localhost:5173' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

Let's split this huge test into smaller tests.

CI is failing: https://github.com/aistomin/deutsch-trainer-backend/actions/runs/4739302782/jobs/8414031252?pr=67

Create an API that creates a test suite of 10 questions.

Let's add https://hitsofcode.com/ to the README file.