fix: improve Msg91 error handling to extract API error messages

[deepshekhardas]

No description provided.

[greptile-apps]

Greptile Summary

This PR improves the error handling in the Msg91 SMS adapter so that when the API returns a non-200 response, the failure result now carries the actual error message extracted from the response body instead of the static string "Unknown error".

• Checks $result['response']['message'] then $result['response']['error'] in order, with is_string guards and a json_encode fallback for non-scalar values.
• Transport-layer failures (network errors, DNS, TLS) still land in the same else branch but the top-level $result['error'] string — populated by request() on ClientExceptionInterface — is not consulted, so those cases still surface as "Unknown error".

Confidence Score: 5/5

The change is self-contained to the error-reporting path and does not affect the successful delivery logic; safe to merge.

The only new finding is a missed opportunity to surface transport-level error strings — a non-blocking quality gap that does not affect correctness of the success path or the overall delivery flow.

Files Needing Attention: No files require special attention beyond the single changed file.

Important Files Changed

Filename	Overview
src/Utopia/Messaging/Adapter/SMS/Msg91.php	Adds structured error-message extraction from API response body (checking message and error keys), with is_string/json_encode guards; does not yet check the top-level $result['error'] for transport-layer failures.

_{Reviews (5): Last reviewed commit: "fix: guard Msg91 error extraction agains..." | Re-trigger Greptile}

[deepshekhardas]

Following up - Msg91 error handling fix. Let me know if changes needed.