feat(#10846): add local_phone mustache helper to strip country code in SMS

[megha1807]

Description

Adds a new local_phone Mustache template helper to message-utils that strips the country code prefix from phone numbers in outgoing SMS messages.

This allows SMS message authors to render phone numbers in local format without modifying stored contact data.

Closes #10846

Usage example

Before: +9779841234567
After: 9841234567

Template syntax:
Contact {{#local_phone}}{{facility_phone}}{{/local_phone}} for help.

The helper reads default_country_code from app_settings. If the phone number starts with +{country_code}, the prefix is stripped. Otherwise the number is returned unchanged. Existing templates without this helper are completely unaffected.

AI Disclosure: I used Claude to understand the codebase structure and explore possible approaches for implementing the Mustache helper. The final implementation, testing, and refinements were done by me, and I verified the behavior with SMS workflows to ensure correctness and backward compatibility.

Code review checklist

• UI/UX backwards compatible
• Readable
• Documented
• Tested
• Internationalised
• Backwards compatible

[megha1807]

@binokaryg All 8 integration test failures are pre-existing flaky tests unrelated to this PR:

• audit.spec.js - timing-sensitive count assertions
• message-duplicates.spec.js - race condition in duplicate detection
• sentinel-api-transitions.spec.js - transition count timing issues

None of these touch message-utils or the local_phone helper added in this PR.
The SMS workflow tests all pass. Ready for review.

[binokaryg]

Thanks @megha1807, I will review this. I will retry the failing tests a few more times if needed.

Meanwhile, please make sure that you have gone through our AI guidelines for contributors.

[megha1807]

Thanks @binokaryg!
Yes, I’ve gone through the AI Assistance Guidelines.

AI Disclosure: I used Claude to understand the codebase structure and explore possible approaches for implementing the Mustache helper. The final implementation, testing, and refinements were done by me, and I verified the behavior with SMS workflows to ensure correctness and backward compatibility.

Please let me know if any changes are needed.

[binokaryg]

AI Disclosure: I used Claude to understand the codebase structure and explore possible approaches for implementing the Mustache helper. The final implementation, testing, and refinements were done by me, and I verified the behavior with SMS workflows to ensure correctness and backward compatibility.

Please let me know if any changes are needed.

Could you please add it to the PR description?

[megha1807]

Thanks @binokaryg, I’ve added the AI disclosure to the PR description.

[binokaryg]

Hi @megha1807, I think the implementation is good.

Could you please add the following scenarios to the tests?

• default_country_code set as a numeric
  e.g.

  cht-core/api/tests/mocha/services/report/smsparser.spec.js

  Line 106 in 4aaf008

  default_country_code: 977,

• phone number that is already in local format e.g. 9841234567

Also a documentation for usage (separate PR on medic/cht-docs) would be helpful for users to discover and use this helper. Would you be able to do it?

[megha1807]

Hi @binokaryg, thank you for reviewing this and for the helpful suggestions. I’ll add the requested test scenarios for numeric "default_country_code" and numbers already in local format.

I’ll also prepare a separate documentation PR in "medic/cht-docs" explaining the usage of this helper so it’s easier for users to discover and implement.

Thanks again - I’ll work on these updates shortly.

[megha1807]

@binokaryg I've added both test cases:

• numeric default_country_code (e.g. 977 instead of '977')
• phone number already in local format (e.g. 9841234567)

Also updated stripCountryCode to handle numeric country codes via String() conversion.

I'll prepare the cht-docs PR for the usage documentation separately.