feat: Make string checks case insensitive

[camdecoster]

Description

Make regex patterns case insensitive and transform keyword string to lowercase before running check.

Closes #80.

Changes

• Make regex patterns case insensitive (except keyword pattern)
• Transform keyword string to lowercase before running check
• Add tests for uppercase letters

Testing

• Be on master
• Call the library with named color with uppercase letters: cs.get("BLUE")
• Note that a null value is returned
• Switch to this branch
• Call the library with named color with uppercase letters: cs.get("BLUE")
• Note that an array of numbers is returned representing the named color

Notes

• Per spec, any keyword should be case insensitive. This includes named colors and functional notations.

[Qix-]

No thank you :) see https://github.com/Qix-/color-string/issues/80#issuecomment-3238721332

[Qix-]

This can just be a /i on the regexes I believe, and then a single .toLowerCase() for the keywords.

[camdecoster]

@Qix- any chance you could review this and #78 in the next week?

[camdecoster]

@Qix- hello! I know you've had a busy time lately. Hopefully things have calmed down. Do you have time to take a look at this PR and #81 next week? Alternatively, I'm happy to step in as a maintainer if that would be helpful.

[Qix-]

Can you rebase? :)

[camdecoster]

I resolved the conflicts. Let me know if you need anything else.

[camdecoster]

@Qix- hello! Do you have time to review this PR next week?

[LitoMore]

I will take a look.

[Qix-]

Thanks! Sorry for the delay. Published as 2.1.4.

[camdecoster]

Awesome! Thanks for the update.