Integrate reCAPTCHA v3 Checkout

My WooCommerce shop is seeing a surge of bot-driven checkouts and I want to put a stop to it by adding Google reCAPTCHA v3 to the checkout form only. I do not need the protection site-wide—just on the pages that actually collect order data—so visitors can browse freely while bots are kept out of the payment flow.

Here is what I’m after:
• Load the reCAPTCHA v3 script and badge only on the checkout page.
• Inject the token field into the WooCommerce checkout, then verify it server-side with a concise PHP solution (Laravel-style structure or a clean WordPress hook is fine; no bulky plugins).
• Block submissions that fall below my chosen score threshold and return a clear, human-friendly error.
• Leave me with a short read-me showing where you placed the code, how to swap site/secret keys, and how to tweak the threshold later.

Everything must keep existing payment gateways, coupons, and shipping calculations intact, and the checkout should still pass caching and optimisation checks.

You may work on a staging clone I provide and hand over the code snippets or a lightweight custom plugin when finished.