docs(stripe): document Phase 9.1 blocked status and live-mode readiness checklist

New: PHASE9_1_STRIPE_TEST_VALIDATION.md — baseline verification, the exact Stripe-credential
search performed (none found), the Stripe architecture review (dynamic price_data, unchanged),
what was proven vs. blocked per the mission's own step list, and the live-mode readiness
checklist. Updated: STRIPE_INTEGRATION_RUNBOOK.md and WINTER_BREAK_LAUNCH_CHECKLIST.md to point
at the new opt-in test and the blocked status. PHASE9_COMMERCE_AND_LAUNCH.md gets a short
addendum. No application code changed this phase — no genuine defect was exposed without real
Stripe traffic, so no regression rerun was required.

docs/WINTER_BREAK_LAUNCH_CHECKLIST.md

@@ -46,6 +46,12 @@ legal reviewer, or Stripe, not from more code.
 
 ## Payments — pending real Stripe credentials
 
+Phase 9.1 searched for Stripe TEST credentials specifically to run real validation and found
+none available anywhere this session could reach — see `docs/
+PHASE9_1_STRIPE_TEST_VALIDATION.md` for the exact search and what Chase needs to provide. A
+permanent, opt-in test (`platform/test/stripe-integration-test.js`) is ready to run the real
+TEST-mode proof the moment `STRIPE_SECRET_KEY`/`STRIPE_WEBHOOK_SECRET` exist.
+
 - [ ] Real Stripe account created/available (live mode).
 - [ ] `STRIPE_SECRET_KEY`/`STRIPE_WEBHOOK_SECRET` (live values) provisioned into production
       configuration only — see `docs/STRIPE_INTEGRATION_RUNBOOK.md`'s "Going live" section.