Don't let non-latin characters in

[wetfloo]

Otherwise you get this

[ghost]

+1, yesterday I got an emoji of a snowman in my snippet :D

[dovvakkin]

same problem, twice seen this file with heart

[codicocodes]

I'd be open to a PR on this. There are a couple of different options on approaches, but I'd consider something like this:

• Add a function which checks if a string includes invalid characters. Unit test on several code examples to ensure it does not exclude valid snippets and correctly excludes invalid challenges.
• Use function to filter out invalid nodes in the data seeding pipeline
• Write a command backfilling current challenges and deletes it if it includes invalid characters

[codicocodes]

Here are some example of commands, including backfills: https://github.com/codicocodes/speedtyper.dev/tree/main/packages/back-nest/src/challenges/commands