docs(website): record that the website-side registration/checkout flow is now built

ced4568/RootNode-academy-website (separate GitHub repo, Chase-authorized access) now implements
docs/WEBSITE_REGISTRATION_AND_CHECKOUT.md's full contract on its own side: public offering
lookup, registration (adult + guardian/minor), agreement acceptance, checkout creation, and a
status-polling success page. Its own stale pricing was also corrected to match docs/
ROOTNODE_PRICING_AND_OFFERS_V1.md. It has nothing to talk to yet -- no real Platform API exists
(Gate 4's hardware blocker, unchanged) -- so every RootNode-facing route there returns a clean
503 until ROOTNODE_API_URL/ROOTNODE_INTEGRATION_KEY point at a real deployment.

Updates PHASE10_LAUNCH_READINESS.md Gate 10 and its matrix row, and WINTER_BREAK_LAUNCH_CHECKLIST.md
and WINTER_BREAK_CAMP_OPERATIONS.md's own website-status notes, all of which previously said
'nobody has built the website-side form yet.'

docs/WINTER_BREAK_LAUNCH_CHECKLIST.md

@@ -55,9 +55,13 @@ piece of hardware that has to come from Chase, a legal reviewer, or Stripe, not
 - [x] **Google Workspace** — COMPLETE. `[email protected]`, `gmail.send` scope,
       domain-wide delegation — validated in Phase 5C (`docs/
       RUNBOOK_GOOGLE_WORKSPACE_EMAIL.md`); deployment to production needs the real server.
-- [x] **Website integration** — COMPLETE. Full contract tested end to end, including against
-      real Stripe. The website itself (separate repo, not RootNode-owned) is live and real;
-      this phase did not access or modify it.
+- [x] **Website integration** — COMPLETE, both sides. Full contract tested end to end on the
+      platform side, including against real Stripe. The website itself (a separate repository,
+      `ced4568/RootNode-academy-website` on GitHub — not this repo) now has the actual
+      registration/agreement/checkout/status flow built against that contract, and its own
+      pricing has been corrected to match `docs/ROOTNODE_PRICING_AND_OFFERS_V1.md`. It has
+      nothing to talk to yet — `ROOTNODE_API_URL`/`ROOTNODE_INTEGRATION_KEY` are unset until a
+      real Platform API exists (every route fails a clean 503, never a 500, in the meantime).
 - [x] **Winter Break price** — COMPLETE. **$399.00 launch ("Founding Cohort") / $449.00
       standard reference, paid in full, no deposit, no payment plan** — founder-approved by
       Chase directly, validated against real Stripe TEST mode at this exact amount, reconfirmed