fix(plugin-ecommerce): pass req to Payload API calls in Stripe adapter

[jhb-dev]

What?

Adds the missing req parameter to all payload.find(), payload.create(), and payload.update() calls in the Stripe adapter's confirmOrder.ts and initiatePayment.ts.

Why?

Without req, hooks on transactions/orders/carts receive an empty request context, and each database call runs in an isolated session — breaking transactional consistency (e.g. order created but cart not marked as purchased on failure).

How?

Pass the existing req (already available in scope) to each Payload API call. Also fixes payload.logger.error calls to use the correct object form per project conventions.

Fixes #15836

[jhb-dev]

The single E2E failure (fields__collections__Date (2/2)) is unrelated to this change — it's a Date field test, not ecommerce. All integration, unit, type, and lint checks pass.

[github-actions]

🚀 This is included in version v3.79.0