Phase 3.7: paid pairing flow + returning chat + extension flip

- Backend: payment_sessions + pairing_failures tables; payment.service.js
  and pairing-failure.service.js (new); rewritten pairing.service.js
  (payment-gated blast + targeted "Curhat lagi" + cancel + fallback);
  rewritten extension.service.js (data-driven auto-approve with offline
  safeguard, charge-at-approval); pricing.service.js (extension tiers
  without free trial); mitra-status.service.js (countAvailableMitras
  cached path); 60s sweeper for stale payment sessions
- Backend routes: client.payment.routes, client.mitra-availability.routes,
  internal/failed-pairings.routes; client.chat.routes rewritten for
  payment-gated start + /returning + /cancel + /fallback-to-blast;
  internal/config.routes adds 4 new keys with Valkey invalidate publish
- client_app: mitra-availability poll, payment screen + notifier, pairing
  notifier rewrite (PairingTargetedWaiting + PairingFailed states),
  targeted-waiting overlay + bestie-unavailable dialog, "Curhat lagi"
  CTA, failed-pairing terminal, extension via payment-session
- mitra_app: PairingRequestType enum, returning-chat 20s countdown
  auto-dismiss, extension card "otomatis disetujui" copy
- control_center: 4 new config rows in Settings, Failed Pairings page
  (filter + paginate + action menu), sidebar + route registered
- Test infrastructure: Vitest backend (7/7 pass), Playwright CC (4/4
  pass), Maestro mobile scaffold (CLI install pending)
- Bugs found via Playwright + fixed: LoginPage labels not associated
  with inputs (a11y); backend internal CORS missing PATCH/PUT/DELETE
  in allow-methods (silent settings breakage in browsers since Stage 4)
- Docs: phase3.7.md PRD, phase3.7-plan.md, phase3.7-questions.md (Q&A),
  phase3.7-testing.md (E2E checklist), phase3.7-test-run-2026-05-03.md
  (today's run results)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

control_center/src/core/constants.js

@@ -0,0 +1,46 @@
+// Frontend mirror of selected backend enums (backend/src/constants.js).
+// Keep in sync when new values are added on the server.
+
+// Pairing failure cause tags — used by the Failed Pairings screen filter.
+export const PairingFailureCause = Object.freeze({
+  NO_MITRA_AVAILABLE: 'no_mitra_available',
+  ALL_MITRAS_REJECTED: 'all_mitras_rejected',
+  TARGETED_MITRA_OFFLINE: 'targeted_mitra_offline',
+  TARGETED_MITRA_REJECTED: 'targeted_mitra_rejected',
+  TARGETED_MITRA_TIMEOUT: 'targeted_mitra_timeout',
+  PAYMENT_SESSION_EXPIRED: 'payment_session_expired',
+  CUSTOMER_CANCELLED: 'customer_cancelled',
+  EXTENSION_REJECTED: 'extension_rejected',
+  EXTENSION_SAFEGUARD_TRIPPED: 'extension_safeguard_tripped',
+})
+
+export const PairingFailureCauseLabel = Object.freeze({
+  [PairingFailureCause.NO_MITRA_AVAILABLE]: 'No mitra available',
+  [PairingFailureCause.ALL_MITRAS_REJECTED]: 'All mitras rejected',
+  [PairingFailureCause.TARGETED_MITRA_OFFLINE]: 'Targeted mitra offline',
+  [PairingFailureCause.TARGETED_MITRA_REJECTED]: 'Targeted mitra rejected',
+  [PairingFailureCause.TARGETED_MITRA_TIMEOUT]: 'Targeted mitra timeout',
+  [PairingFailureCause.PAYMENT_SESSION_EXPIRED]: 'Payment session expired',
+  [PairingFailureCause.CUSTOMER_CANCELLED]: 'Customer cancelled',
+  [PairingFailureCause.EXTENSION_REJECTED]: 'Extension rejected',
+  [PairingFailureCause.EXTENSION_SAFEGUARD_TRIPPED]: 'Extension safeguard tripped',
+})
+
+// Operator actions on a failed-pairing row.
+export const PairingFailureOperatorAction = Object.freeze({
+  REFUNDED: 'refunded',
+  CREDITED: 'credited',
+  NO_ACTION: 'no_action',
+})
+
+export const PairingFailureOperatorActionLabel = Object.freeze({
+  [PairingFailureOperatorAction.REFUNDED]: 'Refunded',
+  [PairingFailureOperatorAction.CREDITED]: 'Credited',
+  [PairingFailureOperatorAction.NO_ACTION]: 'No Action',
+})
+
+// Default action when the mitra fails to respond to an extension request in time.
+export const ExtensionTimeoutAction = Object.freeze({
+  AUTO_APPROVE: 'auto_approve',
+  AUTO_REJECT: 'auto_reject',
+})