Improve docker image creation

[aleeusgr]

Description

address #2012

Checklist

• Commit sequence broadly makes sense
• Commits have useful messages
• New tests are added if needed and existing tests are updated
• Any changes are noted in the changelog
• Code is formatted with fourmolu on version 0.17.0.0 (which can be run with scripts/fourmolize.sh)
• Self-reviewed the diff

Migrations

• The pr causes a breaking change of type a,b or c
• If there is a breaking change, the pr includes a database migration and/or a fix process for old values, so that upgrade is possible
• Resyncing and running the migrations provided will result in the same database semantically

If there is a breaking change, especially a big one, please add a justification here. Please elaborate
more what the migration achieves, what it cannot achieve or why a migration is not possible.

[sgillespie]

Thanks for the patch, this is a solid approach! I did run into a few problems testing it: the schema files are missing from the image, and the docs are missing some setup steps.

You correctly mentioned on Discord the requirements were vague. I've tried to add some more implementation guidance there. Can you take a look, and let me know what you think?