Create MixpanelService that uses FieldEncryptionService.hashPhoneNumber()
to SHA-256 hash phone numbers before sending to Mixpanel analytics.
- Implement spamBlocked() method with phone number hashing
- Add 16 unit tests verifying hash correctness and API behavior
- Export service from package index
Co-Authored-By: Paperclip <noreply@paperclip.ing>
