Fix Paystack Funding Callback Bug

I have already integrated Paystack on my site and confirmed that both the callback URL and webhook endpoints are reachable. Payments go through and Paystack marks them as “successful,” yet the buyer’s balance never updates on my platform and no error is returned.

I need a developer to:
• Trace the full payment flow, from redirect to webhook, and pinpoint why my credit-wallet routine is being skipped.
• Verify Paystack’s signature on every event and harden the logic so only genuine, successful events trigger a credit.
• Review the secret keys, environment settings, and database update query to be sure nothing is being silently blocked.
• Supply clear notes (or brief code comments) so I can follow what was changed.

Acceptance criteria
1. A live test transaction reflects instantly in the buyer’s wallet.
2. Only a verified “success” event from Paystack can alter balances.
3. Any failure or mismatch is logged with a readable message so future debugging is straightforward.

The codebase is small and focused; once you identify the missed link, the fix should be quick. I’ll provide repository access and sandbox keys as soon as we start.