Replace strong database relations with weak ones

AC:
- TokenProperty should not have user and token, but userId and tokenId
- Check Riddles for similar
- Check Task for similar

Locate the TokenProperty, Riddles, and Task definitions, then compare how their user and token relations are declared. Use the acceptance criteria to identify the corresponding ID fields and check each named entity for similar relations; the work is done when all listed relations match the requested weak form and the project still builds and tests.

Written by the indexing model from the issue text.