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/04-desktop-app.md

@@ -101,7 +101,7 @@ The existing `input-telemetry-handlers` and `suggestion-handlers` IPC extensions
 | `UpdateService` | electron-updater (canonical Forgejo feed, channels, mandatory/full-vs-delta policy, staged rollout, restart dialog) |
 | `AutoLaunchService` | OS login-item auto-start |
 | `LoggerService` | electron-log wrapper + category loggers |
-| `checkout`/payment | `payment-handlers.ts` — authenticated Edge-only Stripe/Payple checkout + server readback |
+| upgrade / billing | No in-app checkout. `license-handlers.ts` `LICENSE.OPEN_BILLING` opens `billingUrl({ tier })` (web Payple); tier returns via `license:tierChanged`. Stripe `payment-handlers.ts`·`CheckoutModal`·`payment:*` IPC removed 2026-09-26 |
 
 ### Ads (`services/ads/`)
 | File | Purpose |
@@ -139,7 +139,6 @@ Registry: `src/main/ipc/index.ts` calls 31 `registerXHandlers()` in fixed order.
 | `meeting-mode-handlers` | MEETING_MODE + MEETING_CHAT |
 | `meeting-summary-handlers` | MEETING_SUMMARY |
 | `memo-handlers` | MEMO |
-| `payment-handlers` | PAYMENT |
 | `rag-handlers` | RAG |
 | `stt-handlers` | STT |
 | `suggestion-handlers` | SUGGESTION + POPUP_SUGGESTION |
@@ -156,7 +155,7 @@ The **`KEYBINDING`** group replaced the old per-action `HOTKEY` group. `HOTKEY`
 
 **`LLM.PROCESS` normalizes at the IPC boundary.** The handler runs `buildInstructionInvocation` itself when `action === 'custom'` with a `customPrompt` (`llm-handlers.ts:94-108`), so the renderer passes the **raw instruction text** and never duplicates the substitution or argument-placement rules. This is what makes `VoiceModeService`, `ChainService`, and `LLM.PROCESS` literally share one implementation. No channel or type changed for this; `LLMProcessParams` is unchanged.
 
-Preload exposes **`window.electronAPI`** with 35 namespaces: `platform, audio, config, voice, stt, keybinding, llm (incl. premium), history, dictionary, stats, window, system, instruction, app, memo, voiceCommand, context, chain, caption, license, fileTranscription, meetingSummary, dictationTemplate, rag, voiceAction, voiceConversation, meetingMode, meetingChat, meetingDocTemplate, cloudSync, onlineAuth, ads, support, payment, inputTelemetry, suggestion`. The `keybinding` bridge is 9 methods mirroring the channels above (`src/preload/index.ts:323`), replacing the 11-method `hotkey` bridge. Envelope: `IPCResult<T>` (success/error); `app.onDataChanged` is the global refresh channel.
+Preload exposes **`window.electronAPI`** with 35 namespaces: `platform, audio, config, voice, stt, keybinding, llm (incl. premium), history, dictionary, stats, window, system, instruction, app, memo, voiceCommand, context, chain, caption, license, fileTranscription, meetingSummary, dictationTemplate, rag, voiceAction, voiceConversation, meetingMode, meetingChat, meetingDocTemplate, cloudSync, onlineAuth, ads, support, inputTelemetry, suggestion`. The `keybinding` bridge is 9 methods mirroring the channels above (`src/preload/index.ts:323`), replacing the 11-method `hotkey` bridge. Envelope: `IPCResult<T>` (success/error); `app.onDataChanged` is the global refresh channel.
 
 ---