chore(js-sdk): add methods to manage promotion codes

[asgerjensen]

Summary

What — What changes are introduced in this PR?

Added functions on store client to allow adding and removing promotion codes.

Why — Why are these changes relevant or necessary?

The functionality is present in the /store api, but not reflected in the javascript client.

It /might/ have been possible before, by using the general update function, but it didn't give a clean way to deal with removals. As the API already exposes the functions, they may as well be made available to the javascript client.

How — How have these changes been implemented?

Added to store client

Testing — How have these changes been tested, or how can the reviewer test the feature?

Built and included in demo repo, to verify typing and functionalty.

---

Examples

Provide examples or code snippets that demonstrate how this feature works, or how it can be used in practice.
This helps with documentation and ensures maintainers can quickly understand and verify the change.

sdk.store.cart.addPromotions("cart_123", {
      promo_codes: ["20OFF"]
 })

sdk.store.cart.removePromotions("cart_123", {
    promo_codes: ["20OFF"]
})

---

Checklist

Please ensure the following before requesting a review:

• I have added a changeset for this PR
  • Every non-breaking change should be marked as a patch
  • To add a changeset, run yarn changeset and follow the prompts
• The changes are covered by relevant tests
• I have verified the code works as intended locally
• I have linked the related issue(s) if applicable

---

Additional Context

Add any additional context, related issues, or references that might help the reviewer understand this PR.
Closes #15068

[changeset-bot]

🦋 Changeset detected

Latest commit: b2ad5c7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 77 packages

Name	Type
@medusajs/js-sdk	Patch
@medusajs/draft-order	Patch
@medusajs/dashboard	Patch
@medusajs/medusa	Patch
@medusajs/admin-bundler	Patch
@medusajs/test-utils	Patch
@medusajs/medusa-oas-cli	Patch
integration-tests-http	Patch
@medusajs/analytics	Patch
@medusajs/api-key	Patch
@medusajs/auth	Patch
@medusajs/caching	Patch
@medusajs/cart	Patch
@medusajs/currency	Patch
@medusajs/customer	Patch
@medusajs/file	Patch
@medusajs/fulfillment	Patch
@medusajs/index	Patch
@medusajs/inventory	Patch
@medusajs/link-modules	Patch
@medusajs/locking	Patch
@medusajs/notification	Patch
@medusajs/order	Patch
@medusajs/payment	Patch
@medusajs/pricing	Patch
@medusajs/product	Patch
@medusajs/promotion	Patch
@medusajs/rbac	Patch
@medusajs/region	Patch
@medusajs/sales-channel	Patch
@medusajs/settings	Patch
@medusajs/stock-location	Patch
@medusajs/store	Patch
@medusajs/tax	Patch
@medusajs/translation	Patch
@medusajs/user	Patch
@medusajs/workflow-engine-inmemory	Patch
@medusajs/workflow-engine-redis	Patch
@medusajs/oas-github-ci	Patch
@medusajs/cache-inmemory	Patch
@medusajs/cache-redis	Patch
@medusajs/event-bus-local	Patch
@medusajs/event-bus-redis	Patch
@medusajs/analytics-local	Patch
@medusajs/analytics-posthog	Patch
@medusajs/auth-emailpass	Patch
@medusajs/auth-github	Patch
@medusajs/auth-google	Patch
@medusajs/caching-redis	Patch
@medusajs/file-local	Patch
@medusajs/file-s3	Patch
@medusajs/fulfillment-manual	Patch
@medusajs/locking-postgres	Patch
@medusajs/locking-redis	Patch
@medusajs/notification-local	Patch
@medusajs/notification-sendgrid	Patch
@medusajs/payment-stripe	Patch
@medusajs/core-flows	Patch
@medusajs/framework	Patch
@medusajs/modules-sdk	Patch
@medusajs/orchestration	Patch
@medusajs/types	Patch
@medusajs/utils	Patch
@medusajs/workflows-sdk	Patch
@medusajs/http-types-generator	Patch
@medusajs/cli	Patch
@medusajs/deps	Patch
@medusajs/telemetry	Patch
@medusajs/admin-sdk	Patch
@medusajs/admin-shared	Patch
@medusajs/admin-vite-plugin	Patch
@medusajs/icons	Patch
@medusajs/toolbox	Patch
@medusajs/ui-preset	Patch
create-medusa-app	Patch
medusa-dev-cli	Patch
@medusajs/ui	Patch

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[vercel]

@asgerjensen is attempting to deploy a commit to the medusajs Team on Vercel.

A member of the Team first needs to authorize it.

[medusa-os-bot]

Thank you for your contribution!

After reviewing this PR, we need a few things addressed before we can move forward:

Required changes:

• Rename addPromotionCodes → addPromotions and removePromotionCodes → removePromotions. The admin SDK uses this naming for the equivalent draft order methods (draftOrder.addPromotions, draftOrder.removePromotions) — store cart methods should be consistent.
• Add a query?: SelectParams parameter to both methods, consistent with every other cart method that returns a cart (e.g. addShippingMethod, transferCart). Without it, callers cannot configure which fields are returned.
• Add tests for the new methods. New functionality must be covered by tests per our contribution guidelines.
• Link a GitHub issue. Non-trivial changes require a linked issue — please open one (or link an existing one) describing the missing SDK methods.

Once these are addressed, another review will be triggered automatically.

Thanks again!

[asgerjensen]

@medusajs-bot review