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/.maestro/flows/02_onboarding_verified.yaml

@@ -1,6 +1,6 @@
-# Phase 4 Stage 2 — verified onboarding path:
-#   Splash → onboarding carousel → Welcome → Display Name → Verif Choice Sheet
-#   (verifikasi nomor HP) → ESP (pick a chip) → USP → Register → OTP (6-digit)
+# Phase 4 — verified onboarding path (post-ESP retirement, 2026-05-12):
+#   Splash → Display Name → Verif Choice Sheet (verifikasi nomor HP) →
+#   USP one-time gate (first-time user → USP screen) → Register → OTP (6-digit)
 #   → S6 paywall (when first-session-discount eligible) or duration picker.
 #
 # Run:
@@ -26,6 +26,7 @@ env:
       BACKEND_INTERNAL_URL: ${BACKEND_INTERNAL_URL}
 - launchApp:
     clearState: true
+# Onboarding carousel (still present per Phase 4 Stage 9 minimum-touch).
 - extendedWaitUntil:
     visible:
       text: "Mulai"
@@ -33,12 +34,14 @@ env:
 - tapOn:
     text: "Mulai"
     retryTapIfNoChange: true
+# Phase 4 Stage 9: /welcome is retired. SHome1st CTA "aku mau curhat"
+# leads into the onboarding flow.
 - extendedWaitUntil:
     visible:
-      text: "Lanjut sebagai Tamu"
+      text: "aku mau curhat"
     timeout: 10000
 - tapOn:
-    text: "Lanjut sebagai Tamu"
+    text: "aku mau curhat"
     retryTapIfNoChange: true
 - extendedWaitUntil:
     visible:
@@ -59,21 +62,14 @@ env:
 - tapOn:
     text: "verifikasi nomor HP"
     retryTapIfNoChange: true
-# ESP screen — pick at least one chip then tap "lanjut"
-- extendedWaitUntil:
-    visible:
-      text: "Lagi mikirin apa?"
-    timeout: 10000
-- tapOn:
-    text: "Hubungan"
-- tapOn:
-    text: "lanjut"
-    retryTapIfNoChange: true
-# USP screen
+# USP one-time gate — first run after clearState, so usp_seen=false → USP shown.
+# Explicitly assert ESP "Lagi mikirin apa?" is NOT visible to catch regression.
 - extendedWaitUntil:
     visible:
       text: "Sebelum mulai"
     timeout: 10000
+- assertNotVisible:
+    text: "Lagi mikirin apa?"
 - tapOn:
     text: "aku ngerti, lanjut"
     retryTapIfNoChange: true