Phase 4 Stage 8: returning-user shell + Tanya Admin sheet

Bestie Choice Sheet on home Mulai Curhat CTA. When the user has at
least one prior session (bestieHistoryHasItemsProvider hits the chat-
sessions history endpoint), the CTA opens a HaloBottomSheet with two
cards: 'bestie yang udah kenal' -> /chat/history, 'bestie baru' ->
/payment/entry. Empty history -> direct to /payment/entry.

Bestie history list visual upgrade: HaloOrb (mitraId seed) + name +
last-session date + topic pills + sessions count + ONLINE pill.
Backend getCustomerHistory now returns topics, mitra_is_online,
sessions_count in a single payload (no per-row presence round-trip).

BestieOfflinePopup with two variants (returning | new_) replacing the
legacy BestieUnavailableDialog. tanya admin ghost CTA on both variants
opens the new TanyaAdminSheet. Stage 5's targeted-wait declined stub
+ Stage 7's chat-screen 409 stub + searching-screen call site all
migrated to the real component.

TanyaAdminSheet: HaloBottomSheet with WA + Telegram buttons, deeplinks
fetched via supportHandlesProvider (CC-config-driven). url_launcher
added to client_app; ios LSApplicationQueriesSchemes covers
https/http/whatsapp/tg.

Stage 2's OTP-blocked popup hubungi admin SnackBar stub also migrated
to TanyaAdminSheet.

Dev-only POST /internal/_test/seed-history-session lets Maestro 08
flow seed a history row before exercising the choice sheet.

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

client_app/lib/features/home/providers/bestie_history_provider.dart

@@ -0,0 +1,50 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../../../core/api/api_client_provider.dart';
+
+class BestieHistoryItem {
+  final String sessionId;
+  final String? mitraId;
+  final String mitraName;
+  final DateTime? endedAt;
+  final List<String> topics;
+  final int sessionsCount;
+  final bool mitraIsOnline;
+
+  const BestieHistoryItem({
+    required this.sessionId,
+    required this.mitraId,
+    required this.mitraName,
+    required this.endedAt,
+    required this.topics,
+    required this.sessionsCount,
+    required this.mitraIsOnline,
+  });
+
+  factory BestieHistoryItem.fromJson(Map<String, dynamic> json) {
+    final endedAtRaw = json['ended_at'];
+    return BestieHistoryItem(
+      sessionId: json['id'] as String,
+      mitraId: json['mitra_id'] as String?,
+      mitraName: json['mitra_display_name'] as String? ?? 'Bestie',
+      endedAt: endedAtRaw is String ? DateTime.tryParse(endedAtRaw)?.toLocal() : null,
+      topics: (json['topics'] as List?)?.cast<String>() ?? const [],
+      sessionsCount: (json['sessions_count'] as num?)?.toInt() ?? 1,
+      mitraIsOnline: json['mitra_is_online'] as bool? ?? false,
+    );
+  }
+}
+
+final bestieHistoryProvider = FutureProvider<List<BestieHistoryItem>>((ref) async {
+  final api = ref.read(apiClientProvider);
+  final response = await api.get('/api/client/chat/history');
+  final items = (response['data']['items'] as List<dynamic>? ?? [])
+      .cast<Map<String, dynamic>>();
+  return items.map(BestieHistoryItem.fromJson).toList();
+});
+
+/// Cheap derived provider used by the home CTA to decide whether to show the
+/// bestie-choice sheet or skip straight into the new-payment flow.
+final bestieHistoryHasItemsProvider = FutureProvider<bool>((ref) async {
+  final items = await ref.watch(bestieHistoryProvider.future);
+  return items.isNotEmpty;
+});