feat: POST /api/routes-b/webhooks/[id]/ping — send test ping to webhook

[kehindefaith26]

Closes #478

What changed

Adds app/api/routes-b/webhooks/[id]/ping/route.ts with a POST handler that sends a signed test ping to a registered webhook's target URL.

How it works

• Authenticates the request via Bearer token (Privy)
• Looks up the UserWebhook by id and verifies ownership
• Builds a { event: 'ping', timestamp, webhookId } payload
• Signs it with HMAC-SHA256 using the webhook's signingSecret
• POSTs to webhook.targetUrl with X-LancePay-Signature: sha256=<sig>
• Returns { success, statusCode, targetUrl } — non-2xx responses set success: false, network errors set statusCode: 0

Acceptance criteria covered

• 200 with { success, statusCode, targetUrl } on success
• Payload is HMAC-signed and sent with the signature header
• Non-2xx from target returns success: false, not a server error
• Network failure returns { success: false, statusCode: 0 }
• 403 if webhook belongs to another user
• 404 if webhook does not exist
• 401 for unauthenticated requests

[vercel]

@kehindefaith26 is attempting to deploy a commit to the david's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@kehindefaith26 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits