[BACKEND] Standardize API error codes with machine-readable problem details

[utksh1]

Problem

SecuScan needs a production-grade improvement in this area: Error response consistency..

Scope

Adopt a shared error schema with code, message, field path, request_id, and remediation hint across core endpoints.

Acceptance Criteria

• The implementation is focused and does not introduce unrelated UI, docs, lockfile, or formatting churn.
• Security-sensitive behavior has explicit negative tests where applicable.
• Existing tests continue to pass, and new tests cover the main success and failure paths.
• Documentation or configuration examples are updated when operator behavior changes.

Verification

Tests should snapshot validation/auth/not-found/conflict responses and ensure legacy string-only errors are removed.

Difficulty

Hard, useful issue intended for experienced contributors.

[advikdivekar]

please assign me this under GSSoC 2026, sharing my implementation plan asap

[Bhavy12-cell]

Hi @utksh1
Please assign me this issue.

[Avnithakur731-a]

Hi @utksh1 👋

I’ve carefully reviewed this issue and explored the related implementation areas in the codebase. The problem statement is clear to me, and I already have an approach in mind for implementing a clean, scalable, and maintainable solution while preserving the existing architecture and coding standards.

I’m actively contributing under GSSoC 2026 and would genuinely love to work on this issue. I can start immediately and will ensure:

• clean and well-documented code
• proper testing and edge-case handling
• regular progress updates
• adherence to project guidelines

Please consider assigning this issue to me. Thank you!