test: add unit tests for DataAnonymizationService (#1281)

[yahayaf84771-afk]

Summary

Closes #1281

Adds src/common/utils/data-anonymization.service.spec.ts — a focused Jest suite for every public method of DataAnonymizationService.

Coverage

Method	Happy-path tests	Edge / failure tests
anonymizeUserData	default options, custom fields, hashIdentifiers=false, keepEmailDomain=false	empty object, 1- and 2-char field values, email without domain, numeric id
anonymizeRecords	array of records, custom options passed through	empty array, original records not mutated
containsPII	all recognised PII field names	null value, undefined value, empty object, no PII fields
removePII	default fields removed, custom field list	empty object, missing fields, original not mutated, empty removal list

Testing

Uses Test.createTestingModule with no external dependencies (service has none). All assertions are pure — no network, DB, or filesystem access.

Checklist

• Every public method has ≥ 1 test
• Both success and failure/edge-case paths are asserted
• No new runtime dependencies introduced
• Existing Jest config unchanged

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[RUKAYAT-CODER]

Well done on the job done so far!
Kindly fix workflow to pass