Add API error handling helper

[github-actions]

Introduce a small API error response helper for the Express app and use it from one route.

Acceptance Criteria

• Keep the pull request focused.
• Include a short summary of the change.
• Link this issue in the pull request description.

/bounty $50

[mr-magaia]

Starting work on this. Model: GPT-5 (Codex). Plan is small: add a shared error response helper for the Express app and use it from one route, keeping the change scoped to this issue.

[KHHH2312]

I am working on this

[KHHH2312]

/attempt #7

Implementation Plan

• Review the core requirements and constraints of the issue.
• Implement the requested changes and add necessary checks/tests.
• Verify functionality locally with testing tools.
• Provide a clear demo of the successful build/test execution in the PR.

[fennhelloworld]

I have implemented the API error handling helper in PR #135. It includes a global error handler middleware that catches all unhandled errors and returns safe responses. Please consider this PR for the bounty.