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>

backend/test/services/pairing.service.test.js

@@ -61,7 +61,7 @@ describe('pairing.service', () => {
     vi.clearAllMocks()
   })
 
-  it('single-recipient general blast → mitra declines → terminates with ALL_MITRAS_REJECTED', async () => {
+  it('single-recipient general blast → mitra declines → retryable ALL_MITRAS_REJECTED, payment stays confirmed', async () => {
     // Arrange: confirmed, non-targeted payment session.
     const pay = await createPaymentSession({
       customerId: customer.id,
@@ -80,7 +80,7 @@ describe('pairing.service', () => {
     // classified as a general-blast all-rejected, NOT a targeted reject.
     await declinePairingRequest(session.id, mitra.id)
 
-    // Assert: pairing_failures row carries ALL_MITRAS_REJECTED, not TARGETED_*.
+    // Assert: pairing_failures audit row carries ALL_MITRAS_REJECTED.
     const sql = db()
     const failures = await sql`
       SELECT cause_tag FROM pairing_failures WHERE payment_session_id = ${pay.id}
@@ -88,16 +88,19 @@ describe('pairing.service', () => {
     expect(failures).toHaveLength(1)
     expect(failures[0].cause_tag).toBe(PairingFailureCause.ALL_MITRAS_REJECTED)
 
-    // Payment session is terminal (failed_pairing) — terminal failures consume the payment.
+    // Payment session stays CONFIRMED — the customer can re-blast on the same
+    // payment via the S7 Timeout "coba cari lagi" CTA.
     const [paySession] = await sql`SELECT status FROM payment_sessions WHERE id = ${pay.id}`
-    expect(paySession.status).toBe(PaymentSessionStatus.FAILED_PAIRING)
+    expect(paySession.status).toBe(PaymentSessionStatus.CONFIRMED)
 
-    // Customer was notified with PAIRING_FAILED carrying the same cause tag.
+    // Customer was notified with PAIRING_FAILED carrying is_terminal=false so
+    // the client renders the retryable variant of the S7 timeout screen.
     const pairingFailedCalls = sendToUser.mock.calls.filter(
       ([, , data]) => data?.type === WsMessage.PAIRING_FAILED,
     )
     expect(pairingFailedCalls).toHaveLength(1)
     expect(pairingFailedCalls[0][2].cause_tag).toBe(PairingFailureCause.ALL_MITRAS_REJECTED)
+    expect(pairingFailedCalls[0][2].is_terminal).toBe(false)
   })
 
   it('cancelPairingRequest does NOT push PAIRING_FAILED to the customer', async () => {