Bug: Webhook POST handler crashes — undefined `request` variable

[FuturMix]

Summary

The POST handler in src/app/api/webhooks/route.js references a bare request variable (line 28) that is not defined in the handler's scope. The withAuth middleware passes a single event object containing { request, locals, context }, but the handler destructures only event.locals and then tries to call request.json() — this throws ReferenceError: request is not defined.

Impact

Creating a webhook always crashes with a 500 error. The GET handler works correctly because it doesn't reference request.

Steps to Reproduce

1. Authenticate and send POST /api/webhooks with a valid body { url: "https://example.com", events: ["message"] }
2. Server crashes with ReferenceError: request is not defined

Fix

Change request.json() to event.request.json() on line 28.