feat: Add errorCode field to TransakService

[imyugioh]

Explanation

This PR adds errorCode support to the TransakDepositOrder type in @metamask/ramps-controller, enabling Transak error codes to flow through to analytics events.

Current state:

• TransakDepositOrder has statusDescription for failed order messages but no structured error code field.
• The RAMPS_TRANSACTION_FAILED Segment event logs error_message but has no way to distinguish specific failure reasons (e.g., KYC incomplete, duplicate order, fraud detection).
• Transak returns errorCode in API error responses (e.g., 4002 for KYC required, 4005 for duplicate order).

What changed:

• Added errorCode?: string to TransakDepositOrder type in TransakService.ts.
• The getOrder() method already spreads the full API response into the return object, so errorCode passes through automatically when present.
• Added unit tests verifying errorCode is passed through when present and undefined when absent.

Why this matters:

• Enables metamask-mobile to include error_code in the RAMPS_TRANSACTION_FAILED analytics event.
• Allows the ramps team to distinguish specific failure reasons instead of seeing generic "Something went wrong" messages.
• Supports root-cause analysis: e.g., "10% of users get error 4002 (KYC incomplete)" vs "orders are failing."

References

Ref: TRAM-3267

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

---

Note

Low Risk
Low risk type-surface change that only adds an optional field and test coverage; runtime behavior is unchanged aside from allowing the API-provided errorCode to be returned to callers.

Overview
Adds errorCode support to deposit orders returned by TransakService. TransakDepositOrder now includes optional errorCode?: string, allowing the orders API response field to pass through to consumers.

Extends getOrder unit coverage to assert errorCode is preserved when present and undefined when absent.

^{Written by Cursor Bugbot for commit e093f3d. This will update automatically on new commits. Configure here.}