Phase 4 checkpoint: chat-screen perf refactor + retryable blast-failure + repo-wide dispose-ref guardrail

Chat-screen performance (customer + mitra):
- Parent screens have zero `ref.watch` — only `ref.listen` for side effects
- Body extracted into its own `ConsumerStatefulWidget`; AppBar parts split
  into narrow `.select` consumers (mode, sensitivity, timer)
- Per-second timer ticks routed to dedicated providers
  (`chatRemainingSecondsProvider` + new `mitraChatRemainingSecondsProvider`)
  so WS `session_tick` frames don't invalidate the rest of the chat state

Dispose-in-ref bug fix:
- `home_screen.dart`, `payment_screen.dart`, `mitra_chat_screen.dart` —
  ref-using cleanup moved from `dispose()` to `deactivate()`. Modern
  Riverpod invalidates `ref` the moment `dispose()` runs; the resulting
  silent error corrupts the widget-tree finalize and the next screen
  appears frozen
- `halo_lints` package added at repo root with `no_ref_in_dispose` rule
  to catch this pattern in CI / IDE analysis
- `custom_lint` activated in both apps' `analysis_options.yaml`
  (was installed but never wired in — also brings `riverpod_lint`'s
  `avoid_ref_inside_state_dispose` online)
- CLAUDE.md Pitfalls section added to client_app + mitra_app

Phase 4 §3 retryable blast-failure (Option A):
- Backend `expirePairingRequest` + all-rejected use
  `recordIntermediateFailure` instead of `failPaymentSession` so the
  payment session stays `confirmed` for re-blast
- WS `pairing_failed` payload carries `is_terminal: false` on the
  retryable paths; client parses the flag and exposes `retryBlast()`
- "Coba cari lagi" CTA on S7 Timeout now re-blasts on the same payment
- Pairing service test updated to reflect the new semantics

Customer waiting-payment screen navigation patch:
- `_navigateTerminal` uses `Future.microtask` + `addPostFrameCallback`
  redundancy after a release-mode bug where polling stopped but
  `context.go` never fired, leaving the screen visually stuck on
  "menunggu pembayaran"

See requirement/resume-2026-05-15.md for next-day pickup checklist
(mitra release rebuild + S21 Ultra install + retest is the gating item).

Bundles unrelated in-flight Phase 4 §2.x work that was already on disk
(ESP screen removal, USP one-time gate scaffolding, bestie-availability
public route, OTP service edits, Maestro flow tweaks) — kept together
to avoid a partial-rebase mess.

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

client_app/lib/main.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/material.dart';
@@ -5,6 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'core/api/api_client_provider.dart';
 import 'core/auth/auth_notifier.dart';
 import 'core/auth/auth_providers_provider.dart';
+import 'core/auth/token_storage.dart';
 import 'core/chat/active_session_notifier.dart';
 import 'core/chat/chat_notifier.dart';
 import 'core/notifications/notification_service.dart';
@@ -14,6 +17,14 @@ import 'router.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
+
+  // Pre-warm flutter_secure_storage. The first call triggers AndroidX
+  // Security MasterKey generation (RSA in Keystore) — fast on hardware-backed
+  // keystores but multi-second on emulator's software-emulated TEE. Kicking
+  // it off here in parallel with Firebase init hides the latency behind the
+  // splash instead of paying it on the user's first interaction.
+  unawaited(TokenStorage().readRefreshToken());
+
   await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
 
   final messaging = FirebaseMessaging.instance;