Add webhook signature verification examples and tests

[Lakes41]

Summary

Strengthen the optional webhook utilities package by adding examples and tests for verifying incoming webhook payloads.

Current Behaviour

The README identifies packages/webhook-utils as optional, but the visible setup does not describe how dashboard or integration services should safely verify webhooks.

Expected Behaviour

The webhook utilities package should include tested verification helpers and copy-ready examples for Next.js route handlers or Node services.

Suggested Implementation

Inspect the current webhook utility implementation, add unit tests for valid signatures, invalid signatures, stale timestamps, malformed headers, and body tampering. Add a Next.js route-handler example showing safe raw-body handling.

Files or Areas Likely Affected

• packages/webhook-utils/src/
• packages/webhook-utils/package.json
• packages/webhook-utils/test/
• apps/dashboard/app/api/
• README.md
• docs/

Acceptance Criteria

• Webhook verification tests cover valid and invalid signatures
• Timestamp replay protection is tested if supported
• Malformed or missing headers are handled safely
• A Next.js-compatible example is documented
• Tests can run through a workspace script
• No webhook secret is exposed in examples

Additional Notes

Assumption: webhook verification is intended to be part of the broader integration surface. If the package is legacy-only, update documentation to clarify its support status.

[bukkybyte]

Let me jump on this and deliver in no time

[rahimatonize]

Hi maintainer, I'd like to take this on. I can review the current webhook utilities package, add comprehensive verification tests for signature validation and common failure cases, and improve the documentation with a Next.js-compatible example that demonstrates secure raw-body handling and webhook verification without exposing secrets.

[jaynomyaro]

Hi! I’m a full-stack developer with a strong blockchain background. I’d love to handle this issue and can deliver a clean, reliable solution. Kindly assign it to me.

[grantfox-oss]

🦊 GrantFox — @rahimatonize has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #24)
2. Your PR will be reviewed by the Adamantine-guild maintainers

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