Phase 5 Xendit: Stages 1-7 (XENDIT_ENABLED=false; Stage 8 pending creds)

Backend
- payment_sessions → payment_requests rename across DB schema + 29 files
- payment.service.js becomes product-agnostic owner: EventEmitter +
  Xendit wrapper + requestPayment / confirmPayment public API; legacy
  aliases retained for existing chat callers
- Webhook handler at POST /api/shared/payment/webhooks/xendit, with
  constant-time token verification (8 vitest cases)
- Server-driven pairing: payment.service emits
  payment_request.confirmed → pairing subscriber starts the blast.
  Legacy POST /chat/request still works during the cutover.
- Reconciliation sweeper extended (re-emits events for confirmed rows
  with no chat session)
- SIGTERM drain + startup reconciliation pass in server.js

Customer app
- waiting_payment_screen opens xendit_invoice_url via
  LaunchMode.inAppBrowserView
- searching / no-bestie / targeted-waiting / pairing-notifier updated
  to consume the new payment_request_id contract
- pending_payments_provider + bestie-unavailable dialog migrated

Dev / testing
- XENDIT_ENABLED=false is the safe default; .env.example documents the
  four new vars
- backend/.dev/xendit-fake-webhook.sh exercises the handler without
  ngrok
- 90/92 backend tests pass (two pre-existing session-timer flakes,
  unrelated); client_app analyzer clean
- requirement/phase5-xendit-plan.md is the canonical reference

Stage 8 (live E2E) blocked on Xendit test-mode keys. The dashboard's
single-webhook-URL constraint will be worked around via a self-poll
script next session.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/src/services/config.service.js

@@ -149,6 +149,22 @@ export const getMitraHeartbeatCadenceSeconds = () => {
   return Number.isFinite(parsed) && parsed >= 5 ? parsed : 30
 }
 
+// --- Phase 5: Xendit integration ---
+//
+// Env-driven (per backend/CLAUDE.md Config-Source Convention). All five values
+// read from process.env at call time so test setups can inject via vi.stubEnv.
+// When `enabled` is true, payment.service.js mints a real Xendit invoice on
+// requestPayment(); when false, invoice creation is skipped and the dev/Maestro
+// stub /internal/_test/force-confirm-payment plays the role of the webhook.
+// See requirement/phase5-xendit-plan.md D6/D9.
+export const getXenditConfig = () => ({
+  enabled: process.env.XENDIT_ENABLED === 'true',
+  secretKey: process.env.XENDIT_SECRET_KEY ?? '',
+  webhookToken: process.env.XENDIT_WEBHOOK_TOKEN ?? '',
+  successRedirectUrl: process.env.XENDIT_SUCCESS_REDIRECT_URL ?? '',
+  failureRedirectUrl: process.env.XENDIT_FAILURE_REDIRECT_URL ?? '',
+})
+
 export const getMitraPingConfig = async () => {
   const [requireRow] = await sql`SELECT value FROM app_config WHERE key = 'require_mitra_ping'`
   const [staleRow] = await sql`SELECT value FROM app_config WHERE key = 'mitra_stale_after_seconds'`
@@ -291,18 +307,18 @@ export const setCcLoginLockoutConfig = async ({ max_attempts, lockout_minutes })
 
 // --- Paid Pairing Flow + Returning-Chat + Extension Flip ---
 
-export const getPaymentSessionTimeoutMinutes = async () => {
-  const [row] = await sql`SELECT value FROM app_config WHERE key = 'payment_session_timeout_minutes'`
-  return { payment_session_timeout_minutes: row?.value?.value ?? 20 }
+export const getPaymentRequestTimeoutMinutes = async () => {
+  const [row] = await sql`SELECT value FROM app_config WHERE key = 'payment_request_timeout_minutes'`
+  return { payment_request_timeout_minutes: row?.value?.value ?? 20 }
 }
 
-export const setPaymentSessionTimeoutMinutes = async (value) => {
+export const setPaymentRequestTimeoutMinutes = async (value) => {
   await sql`
     INSERT INTO app_config (key, value, updated_at)
-    VALUES ('payment_session_timeout_minutes', ${sql.json({ value })}, NOW())
+    VALUES ('payment_request_timeout_minutes', ${sql.json({ value })}, NOW())
     ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()
   `
-  return { payment_session_timeout_minutes: value }
+  return { payment_request_timeout_minutes: value }
 }
 
 export const getReturningChatConfirmationTimeoutSeconds = async () => {