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/core/chat/chat_notifier.dart

@@ -456,10 +456,18 @@ class Chat extends _$Chat {
 
       case WsMessage.extensionResponse:
         final accepted = data['accepted'] as bool? ?? false;
+        // On accept, the backend includes the freshly-extended `expires_at` so
+        // the local ticker can resume immediately (otherwise it would be stuck
+        // at 0 / the just-expired moment until the next SESSION_TIMER ping).
+        final extendedExpiresAtRaw = data['expires_at'] as String?;
+        final extendedExpiresAt = (accepted && extendedExpiresAtRaw != null)
+            ? DateTime.tryParse(extendedExpiresAtRaw)?.toLocal()
+            : null;
         state = current.copyWith(
           extensionResponse: data,
           sessionPaused: accepted ? false : current.sessionPaused,
           sessionExpired: accepted ? false : current.sessionExpired,
+          expiresAt: extendedExpiresAt ?? current.expiresAt,
         );
         break;
 

client_app/lib/core/chat/chat_notifier.g.dart

@@ -30,7 +30,7 @@ final chatRemainingSecondsProvider = AutoDisposeStreamProvider<int>.internal(
 @Deprecated('Will be removed in 3.0. Use Ref instead')
 // ignore: unused_element
 typedef ChatRemainingSecondsRef = AutoDisposeStreamProviderRef<int>;
-String _$chatHash() => r'f9d77e176acb682dc6477635e0e80a09e846988b';
+String _$chatHash() => r'a42bf404f5b38034c6c9511259b64b1092af3caa';
 
 /// See also [Chat].
 @ProviderFor(Chat)

client_app/lib/core/chat/session_closure_notifier.g.dart

@@ -6,7 +6,7 @@ part of 'session_closure_notifier.dart';
 // RiverpodGenerator
 // **************************************************************************
 
-String _$sessionClosureHash() => r'521e57f74805faf01f11778872cb37ceae683a5b';
+String _$sessionClosureHash() => r'a9aaf26da64d3489497d057e2b05741c08444e07';
 
 /// See also [SessionClosure].
 @ProviderFor(SessionClosure)