fix: handle invalid luhn checksum input

[suzunn]

Problem

Luhn Checksum currently lets invalid input characters escape as a raw JavaScript error when the character is not valid for the selected radix. For example, Luhn_Checksum(4) with input o reports Character: o is not valid in radix 4. as an unhandled error.

Solution

I wrapped the checksum/check-digit calculation in the operation runner and rethrow validation failures as OperationError, matching the existing controlled operation error path used for invalid radix arguments. I also added regression coverage for the radix 4 invalid-character case from #2536.

Fixes #2536.

Testing

• npx grunt configTests
• node --no-warnings --no-deprecation --openssl-legacy-provider tests\operations\index.mjs --grep Luhn
• npx eslint src\core\operations\LuhnChecksum.mjs tests\operations\tests\LuhnChecksum.mjs
• git diff --check

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