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>

mitra_app/lib/features/chat/screens/mitra_chat_screen.dart

@@ -459,6 +459,10 @@ class _MitraChatScreenState extends ConsumerState<MitraChatScreen> {
     final isResponding = extState is ExtensionRespondingData;
     final topic = TopicSensitivity.fromString(request['topic_sensitivity'] as String?);
     final isSensitive = topic == TopicSensitivity.sensitive;
+    // Extensions auto-approve on mitra non-response (server-side, with connectivity
+    // safeguards). Surface the configured timeout to the mitra so they know what
+    // "no response" means in this card.
+    final timeoutSeconds = request['timeout_seconds'] as int?;
 
     return Container(
       color: isSensitive ? SensitivityTheme.sensitive.bgTint : null,
@@ -477,6 +481,18 @@ class _MitraChatScreenState extends ConsumerState<MitraChatScreen> {
             ],
             const SizedBox(height: 8),
             Text('Customer ingin perpanjang $duration menit', textAlign: TextAlign.center),
+            if (timeoutSeconds != null) ...[
+              const SizedBox(height: 12),
+              Text(
+                'Tidak menjawab dalam $timeoutSeconds detik = otomatis disetujui',
+                textAlign: TextAlign.center,
+                style: TextStyle(
+                  fontSize: 13,
+                  color: Colors.grey.shade700,
+                  fontStyle: FontStyle.italic,
+                ),
+              ),
+            ],
             const SizedBox(height: 24),
             if (isResponding)
               const CircularProgressIndicator()