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/pubspec.lock

@@ -1157,6 +1157,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.0"
+  url_launcher:
+    dependency: "direct main"
+    description:
+      name: url_launcher
+      sha256: f6a7e5c4835bb4e3026a04793a4199ca2d14c739ec378fdfe23fc8075d0439f8
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.2"
+  url_launcher_android:
+    dependency: transitive
+    description:
+      name: url_launcher_android
+      sha256: "3bb000251e55d4a209aa0e2e563309dc9bb2befea2295fd0cec1f51760aac572"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.29"
+  url_launcher_ios:
+    dependency: transitive
+    description:
+      name: url_launcher_ios
+      sha256: "580fe5dfb51671ae38191d316e027f6b76272b026370708c2d898799750a02b0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.4.1"
+  url_launcher_linux:
+    dependency: transitive
+    description:
+      name: url_launcher_linux
+      sha256: d5e14138b3bc193a0f63c10a53c94b91d399df0512b1f29b94a043db7482384a
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.2"
+  url_launcher_macos:
+    dependency: transitive
+    description:
+      name: url_launcher_macos
+      sha256: "368adf46f71ad3c21b8f06614adb38346f193f3a59ba8fe9a2fd74133070ba18"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.5"
+  url_launcher_platform_interface:
+    dependency: transitive
+    description:
+      name: url_launcher_platform_interface
+      sha256: "552f8a1e663569be95a8190206a38187b531910283c3e982193e4f2733f01029"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
+  url_launcher_web:
+    dependency: transitive
+    description:
+      name: url_launcher_web
+      sha256: "85c81589622fbc87c1c683aaea164d3604a7777495a79d91e39ffcdec39ddb34"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.3"
+  url_launcher_windows:
+    dependency: transitive
+    description:
+      name: url_launcher_windows
+      sha256: "712c70ab1b99744ff066053cbe3e80c73332b38d46e5e945c98689b2e66fc15f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.5"
   uuid:
     dependency: transitive
     description: