refactor(billing): remove Stripe; payments are Payple (web) and Google Play (mobile)

Stripe is not used. Keeping its checkout, portal and webhook paths meant a
second payment provider, a second return-URL format and dead UI.

- Delete the stripe-checkout, stripe-portal and stripe-webhook functions and
  their config; billing-catalog serves Payple prices only, and the web parser
  rejects a catalog that still mixes in Stripe prices.
- Web: drop the Stripe checkout/portal buttons, provider toggle and return
  notices; billing shows Payple only. Past rows with provider='stripe' are
  still displayed ("Stripe (종료)") with a support contact instead of a portal.
- Desktop: delete the Stripe checkout modal, payment IPC channels, preload
  namespace and their types; "Remove ads with Pro" opens the web billing page
  via license.openBilling. Support/refund copy names Payple.
- billingUrl() loses the Stripe-only success/canceled result option; the
  Deno contract is regenerated.
- Migrations and the DB's accepted provider values are untouched (history).
- Docs and the backlog record the removal (MON-04, EXT-STRIPE-01, GAP-BILL-03).

Verified: typecheck (desktop/web/admin/api-client/mobile), contract:check,
deno check all functions, deno test 80/80, desktop 1478/1480 on the Electron
runtime (2 known environment failures), web and admin builds, release
metadata and mobile boundary self-tests, eslint on changed files.

docs/map/09-supabase-backend.md

@@ -21,7 +21,7 @@
 | Teams | team invites, membership, roles, `team_activities` feed (`20260913000033`) |
 | Knowledge / RAG | `knowledge_documents`, `knowledge_chunks`, pgvector |
 | Notifications / push | push tokens, durable outbox |
-| Billing | Payple, Stripe, subscriptions, payment provider events/operations |
+| Billing | Payple, subscriptions, payment provider events/operations (`'stripe'` provider values kept only for historical rows) |
 | Admin | admin roles, audit log, atomic admin RPCs |
 | Mobile platform | mobile platform/monetization/runtime integrity |
 | Commands | atomic command reorder |
@@ -48,7 +48,6 @@ Migration numbering referenced in SSOT goes up to `00028`; CI verifies `migratio
 | `account-delete` | Account deletion cascade + provider unlink |
 | `admin-users` / `admin-subscriptions` / `admin-payments` / `admin-audit-log` | Admin operations |
 | `billing-catalog` | Server pricing catalog. Prices/quotas read `PLAN_PRICE_KRW`/`PLAN_QUOTA` from `functions/_shared/core-contract.generated.ts`, generated from `packages/core/src/plan-catalog.ts` by `scripts/ci/sync-core-contract.mjs` (`npm run contract:check` fails on drift; added 2026-09-26, Wave 3, 88f24d8) |
-| `stripe-checkout` / `stripe-portal` / `stripe-webhook` | Stripe billing |
 | `payple-checkout` / `payple-manage` / `payple-renew` / `payple-webhook` | Payple billing (Korea) |
 | `iap-verify` | Google Play / App Store purchase verification |
 | `admob-ssv` | AdMob server-side verification + reward ledger |
@@ -92,7 +91,7 @@ Shared TS types for these live in `packages/api-client` (SSOT).
 
 - Auth (email + Google/GitHub/Apple), RLS, storage, realtime: **implemented**; production Auth + Google provider entry verified GREEN; GitHub/Apple provider secrets and mobile consent callback pending (external).
 - STT/LLM proxies: **implemented** and fail-closed (no synthetic transcripts); atomic quota reservations verified with 20-way concurrency.
-- Billing (Stripe + Payple + IAP verify + webhooks/RTDN): **implemented**; live provider end-to-end and Payple webhook signature verification pending.
+- Billing (Payple + IAP verify + webhooks/RTDN; Stripe removed 2026-09-26): **implemented**; live provider end-to-end and Payple webhook signature verification pending.
 - Ads (AdMob SSV, rewarded ledger, replay protection): **implemented** (Edge v13 ACTIVE); production AdMob serving blocked externally (review/serving limits/store link/payment profile).
 - Push: Supabase owns tokens/devices/outbox/retries. Transports implemented for **FCM, Web Push (VAPID + RFC 8291), and APNs (.p8 token)**; the Cloudflare Worker cron drains the outbox every minute. Android still requires FCM at the device. Details: `docs/deployment/push-transport-without-firebase.md`.
 - Content safety: generation receipts + `content-report` **implemented**.