Phase 4 Stage 10 follow-up: restore BestieHistoryList picker for §4 curhat-lagi

The original Stage 10 plan retired chat_history_screen.dart on the
assumption that the new Chat tab Selesai sub-tab replaced it. That was
wrong: Figma has two distinct screens — `extras.jsx::SChatList` (the
Chat tab, browse-only) and `v4.jsx::BestieHistoryList` (the picker for
mermaid §4 returning-user curhat-lagi). They serve different purposes
on row tap: Selesai opens transcript, BestieHistoryList picks a past
bestie for targeted-pair.

Restoring BestieHistoryList at a new home:

- New screen `features/home/screens/bestie_history_list_screen.dart`
  matching Figma `v4.jsx::BestieHistoryList`:
    appBar title "bestie kamu sebelumnya"
    subtitle "{N} bestie yang pernah nemenin kamu"
    row: orb + "bestie {name}" + ONLINE pill + sessions count + last
         date + topic + → arrow
    row tap (online) → /payment with targetedMitraId (Stage-3 flow)
    row tap (closing-grace) → /chat/session/$id to finish goodbye
    row (offline) → dimmed, tap disabled

  Drops the per-row "curhat lagi" secondary button — the row tap IS the
  pick action now (cleaner, matches Figma).

- New route `/bestie/history` in router.dart; cleanly separated from the
  /chat/* family (which is now exclusively the Chat tab).

- BestieChoiceSheet "bestie yang udah kenal" re-pointed from /chat to
  /bestie/history.

- Stage 8 Maestro flow `08_returning_targeted.yaml` updated to assert
  the new screen title + tap the row by name (uses output.MITRA_NAME
  from the seed_history_session script).

- TECH_DEBT entry retired (curhat-lagi entry point restored). New
  TECH_DEBT entry tracks the still-pending wire-up of the Bestie
  Offline Popup variant for offline-row tap per mermaid §4.

flutter analyze clean (one pre-existing widget_test scaffolding error
unrelated to Stage 10).

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

client_app/lib/router.dart

@@ -12,6 +12,7 @@ import 'features/onboarding/screens/notif_gate_screen.dart';
 import 'features/onboarding/screens/usp_screen.dart';
 import 'features/splash/splash_screen.dart';
 import 'features/home/home_screen.dart';
+import 'features/home/screens/bestie_history_list_screen.dart';
 import 'features/profile/profile_screen.dart';
 import 'core/constants.dart';
 import 'features/chat/screens/searching_screen.dart';
@@ -256,6 +257,13 @@ GoRouter buildRouter(Ref ref) {
       GoRoute(path: '/chat/transcript/:sessionId', builder: (context, state) {
         return ChatTranscriptScreen(sessionId: state.pathParameters['sessionId']!);
       }),
+      // Returning-user `curhat lagi` picker (mermaid §4). Reached from
+      // BestieChoiceSheet → "bestie yang udah kenal". Tap row → targeted-pair
+      // payment. Separate from the Chat tab (which is browse-only).
+      GoRoute(
+        path: '/bestie/history',
+        builder: (_, __) => const BestieHistoryListScreen(),
+      ),
     ],
   );
 }