Phase 4 §2 + §1/§4: OnboardingIntent post-OTP routing + test naming + register-screen overflow

Spec §2 (flow_customer.mermaid) routes post-OTP based on user-lookup +
has_transacted, but the implementation previously dumped every OTP
success on /home. Introduce `OnboardingIntent` provider: set to
`onboarding` by routeForVerifChoice's verified branch (the "aku mau
curhat" transaction journey), set to `recover` by SHome1st's masuk →
banner. Router redirect on AuthAuthenticatedData+isAuthRoute consumes it:
`onboarding` → /payment/entry (dispatches S6 paywall vs PickMethod via
first_session_discount.eligible); `recover` → /home. Intent is reset in
/payment/entry's initState so subsequent masuk → flows don't inherit it.

auth_notifier.verifyOtp uses .copyWithPrevious on AsyncError so
valueOrNull retains AuthOtpSentData/AuthAnonymousData through OTP
failures — required for the OTP-blocked recovery path
(/onboarding/anon/method → /payment/method-pick) to clear the global
redirect without bouncing to /home. Router also extends the
isAuthRoute/isOnboardingFlow carve-out to AuthOtpSentData.

Maestro tests adopt `ts-<app>-<NN>-<MM>-<descriptor>.yaml` convention:
NN = mermaid section, MM = sub-flow index. New ts-customer-02-01..05
cover the §2 branches (verified brand-new → S6, existing-no-tx → S6,
existing-tx → method-pick, OTP-blocked → method-pick, anonymous first-
timer → method-pick); deferred 02-06/07/08/09 documented in
README_section_02.md. TS-07 → ts-customer-02-10 (masuk → recovery);
TS-01..06 → ts-customer-04-01..06 (§4 returning-user). Shared
onboarding_new_user_verified.yaml subflow extracted.

Register screen's body Column now uses LayoutBuilder + SingleChildScrollView
+ ConstrainedBox + IntrinsicHeight so the keyboard-open layout no
longer overflows by 1.3 px (verified visually).

Spec prose updated at flow_customer.mermaid §2 to describe the
intent-driven routing + login-vs-transaction divergence.

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

client_app/lib/features/auth/widgets/verif_choice_sheet.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/auth/onboarding_intent_provider.dart';
 import '../../../core/theme/halo_tokens.dart';
 import '../../../core/theme/widgets/widgets.dart';
 import '../../onboarding/usp_seen_provider.dart';
@@ -81,6 +82,10 @@ Future<void> routeForVerifChoice(
   if (!context.mounted) return;
   switch (choice) {
     case VerifChoice.verified:
+      // §2 transaction CTA path — router consumes this post-OTP and routes
+      // to /payment/entry (S6 paywall vs PickMethod via first_session_discount).
+      ref.read(onboardingIntentProvider.notifier).state =
+          OnboardingIntent.onboarding;
       context.push(seen ? '/auth/register' : '/onboarding/verif/usp');
       break;
     case VerifChoice.anonymous: