feat(isIdentityCard): add NL locale

[RobinvanderVliet]

I have added a Dutch validation method to isIdentityCard.

References

• https://nl.wikipedia.org/wiki/Burgerservicenummer
• https://www.rijksoverheid.nl/onderwerpen/privacy-en-persoonsgegevens/vraag-en-antwoord/wat-is-het-burgerservicenummer-bsn

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable)
• Tests written (where applicable)
• References provided in PR (where applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (88e0d3d) to head (1bc432e).
⚠️ Report is 11 commits behind head on master.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files          114       114           
  Lines         2590      2596    +6     
  Branches       659       659           
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+ Hits          2590      2596    +6     

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[WikiRik]

Not sure about this one, the BSN is comparable to the American Social Security Number, but it's not the document number of Dutch identity cards. We might need to do further review on what the isIdentityCard really validates and possibly change the name so it is clear.
In my view right now we should have three validators; isIdentityCard, isPassportNumber and a third that checks for cases like the BSN and the SSN

[RobinvanderVliet]

Not sure about this one, the BSN is comparable to the American Social Security Number, but it's not the document number of Dutch identity cards. We might need to do further review on what the isIdentityCard really validates and possibly change the name so it is clear. In my view right now we should have three validators; isIdentityCard, isPassportNumber and a third that checks for cases like the BSN and the SSN

I have checked some of the already implemented validator functions in the file, and the validator functions for Finland, Israel, Norway and Spain all seem to check national ID numbers. There might be others that are similar, I have not had time to check them all.

Similar to Dutch cards, Norwegian ID cards have the document number on the front side and the national ID number on the reverse side. The Norwegian validator checks the national ID number.

[Copilot]

Pull request overview

Adds Dutch (NL) support to isIdentityCard by validating BSN numbers (11-proef), with accompanying fixtures and documentation update.

Changes:

• Add NL locale implementation to src/lib/isIdentityCard.js using 11-proef check-digit logic.
• Add NL valid/invalid fixtures to test/validators.test.js.
• Document NL as a supported isIdentityCard locale in README.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
test/validators.test.js	Adds NL fixtures to the identity card validator test matrix.
src/lib/isIdentityCard.js	Implements NL (BSN/11-proef) validation logic.
README.md	Updates isIdentityCard locale list to include NL.

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