Gatekeeper technical specification: need to integrate a payments system into the engineering blog so some stories ca

This issue was opened automatically by Grab Bridge to publish the gatekeeper-approved technical specification for the requested change.

Requested change slug: `need-to-integrate-a-payments-system-into-the-eng`

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## Summary
Implement the requested change inside the guarded repository scope: engineering-blog, TalkToFigmaDesktop, grabpay-merchant-sdk.

## Repository Scope
- engineering-blog
- TalkToFigmaDesktop
- grabpay-merchant-sdk

## Agreed Change Plan
- Requested change: need to integrate a payments system into the engineering blog so some stories can be made premium and only paying users can access them
- Keep the blast radius limited to the files and interfaces identified during analysis.
- Preserve compatibility across any affected repositories and contracts surfaced during review.

## Repository-by-Repository Work
### engineering-blog
- Apply the agreed change within this guarded repository.
- Keep behavior aligned with the architect and gatekeeper review.
- Validate cross-repository assumptions before merge.
- Review and update js/search.js

### TalkToFigmaDesktop
- Apply the agreed change within this guarded repository.
- Keep behavior aligned with the architect and gatekeeper review.
- Validate cross-repository assumptions before merge.
- Review the repository surfaces that implement or consume the agreed change contract.

### grabpay-merchant-sdk
- Apply the agreed change within this guarded repository.
- Keep behavior aligned with the architect and gatekeeper review.
- Validate cross-repository assumptions before merge.
- Review the repository surfaces that implement or consume the agreed change contract.

## Validation Plan
- Add or update unit tests for the directly changed code paths.
- Add integration or contract checks where repository boundaries are touched.
- Re-run the review scenarios that the gatekeeper focused on during the trial.

## Deployment and Rollback
- Roll out the primary repository first unless a shared contract requires coordinated deployment.
- Monitor the user-facing or contract-facing behavior identified in the analysis.
- Prepare a rollback that reverts the guarded repositories to the last known compatible state.

## Open Questions
- Confirm any unresolved assumptions from the gatekeeper review before implementation.