Phase 4 Stage 2: onboarding redesign (client_app + mitra_app)

Verif Choice Sheet on display_name_screen drives the user into either
the verified or anonymous onboarding sub-flow. ESP screen (12 chips,
multi-select, info-only) + USP screen are shared between both branches;
selections persist through to chat_sessions.topics on session start.

OTP-blocked popup (HaloPopup) listens for the four real OTP-rate-limit
error codes (OTP_RATE_LIMIT_PHONE, OTP_RATE_LIMIT_IP, OTP_COOLDOWN,
OTP_ATTEMPTS_EXCEEDED) and drops the user onto the anonymous path with
ESP/USP state preserved.

Auth-providers gating replaces the --dart-define=ENABLE_SOCIAL_AUTH
build flag with server-driven discovery. authProvidersProvider preloads
GET /api/shared/auth-providers at cold start; welcome/register/
force-register screens render Google/Apple buttons only when the
backend reports enabled:true. Falls back to phone-OTP-only when both
providers are off. social_auth_enabled.dart deleted; client_app/CLAUDE.md
updated to reflect the new gating contract.

Mitra app: chat screen renders an ESP chip strip above the first message
bubble when chat_sessions.topics is non-empty.

Backend session.service.js getSessionById SELECTs cs.topics so the mitra
side can read the customer's selected topics.

Maestro flows 02_onboarding_verified.yaml + 03_onboarding_anon.yaml.

Deviation from plan: plan referenced OTP error code 'otp_retry_exhausted';
real codes are OTP_RATE_LIMIT_*/OTP_COOLDOWN/OTP_ATTEMPTS_EXCEEDED -
popup listens for all four. Plan said 'has_paid_first_session'; live
endpoint returns 'has_consulted_before' - used the live field.

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

client_app/lib/features/auth/screens/welcome_screen.dart

@@ -1,39 +1,84 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/auth/auth_notifier.dart';
+import '../../../core/auth/auth_providers_provider.dart';
+import '../../../core/theme/halo_tokens.dart';
+import '../../../core/theme/widgets/widgets.dart';
 
-class WelcomeScreen extends StatelessWidget {
+class WelcomeScreen extends ConsumerWidget {
   const WelcomeScreen({super.key});
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
+    final providersAsync = ref.watch(authProvidersProvider);
+    final providers =
+        providersAsync.valueOrNull ?? AuthProvidersConfig.fallback;
+
     return Scaffold(
       body: SafeArea(
         child: Padding(
-          padding: const EdgeInsets.all(24),
+          padding: const EdgeInsets.all(HaloSpacing.s24),
           child: Column(
             mainAxisAlignment: MainAxisAlignment.center,
             crossAxisAlignment: CrossAxisAlignment.stretch,
             children: [
+              const Center(child: HaloOrb(seed: 0, size: 96, label: 'H')),
+              const SizedBox(height: HaloSpacing.s24),
               const Text(
                 'Halo Bestie',
-                style: TextStyle(fontSize: 32, fontWeight: FontWeight.bold),
+                style: TextStyle(
+                  fontFamily: HaloTokens.fontDisplay,
+                  fontSize: 32,
+                  fontWeight: FontWeight.w700,
+                  color: HaloTokens.ink,
+                ),
                 textAlign: TextAlign.center,
               ),
-              const SizedBox(height: 8),
+              const SizedBox(height: HaloSpacing.s8),
               const Text(
                 'Tempat curhat kamu',
-                style: TextStyle(fontSize: 16, color: Colors.grey),
+                style: TextStyle(
+                  fontFamily: HaloTokens.fontBody,
+                  fontSize: 15,
+                  color: HaloTokens.inkSoft,
+                ),
                 textAlign: TextAlign.center,
               ),
-              const SizedBox(height: 48),
-              ElevatedButton(
+              const SizedBox(height: HaloSpacing.s48),
+              HaloButton(
+                label: 'Lanjut sebagai Tamu',
+                fullWidth: true,
                 onPressed: () => context.push('/auth/display-name'),
-                child: const Text('Lanjut sebagai Tamu'),
               ),
-              const SizedBox(height: 12),
-              OutlinedButton(
+              const SizedBox(height: HaloSpacing.s12),
+              if (providers.google) ...[
+                HaloButton(
+                  label: 'lanjut dengan Google',
+                  icon: const Icon(Icons.g_mobiledata),
+                  variant: HaloButtonVariant.secondary,
+                  fullWidth: true,
+                  onPressed: () =>
+                      ref.read(authProvider.notifier).loginGoogle(),
+                ),
+                const SizedBox(height: HaloSpacing.s12),
+              ],
+              if (providers.apple) ...[
+                HaloButton(
+                  label: 'lanjut dengan Apple',
+                  icon: const Icon(Icons.apple),
+                  variant: HaloButtonVariant.secondary,
+                  fullWidth: true,
+                  onPressed: () =>
+                      ref.read(authProvider.notifier).loginApple(),
+                ),
+                const SizedBox(height: HaloSpacing.s12),
+              ],
+              HaloButton(
+                label: 'Daftar / Masuk',
+                variant: HaloButtonVariant.ghost,
+                fullWidth: true,
                 onPressed: () => context.push('/auth/register'),
-                child: const Text('Daftar / Masuk'),
               ),
             ],
           ),