Phase 3 testing fixes: Fastify 5, SSE→WebSocket+FCM, enums, security, session lifecycle

- Upgrade Fastify 4→5 with all plugins (@fastify/websocket 11, cors 11, sensible 6)
- Migrate all SSE endpoints to WebSocket + FCM push (mitra chat requests, customer pairing status)
- Add flutter_local_notifications for foreground push notifications with sound
- Add splash screen to both apps (hide auth loading flash)
- Introduce constants/enums across entire codebase (no raw string literals)
- Move price tiers from hardcoded array to app_config DB (data-driven, includes 1-min test tier)
- Add session ownership validation on all shared chat routes
- Add ownership checks on endSession, respondToExtension, requestExtension
- Fix session timer: auto-complete expired/stale sessions on server restart
- Add 5-min grace period for abandoned closing sessions
- Fix extension flow: proper session_resumed handling, clearExtensionRequest, closure grace timer cleanup
- Fix chat screens: ConnectChat in initState, session status check on connect
- Fix customer expired view: 5-min countdown, closure state priority over expired state
- Fix mitra extension UI: loading spinner, disable buttons, handle EXTENSION_RESOLVED error
- Fix GoRouter navigation consistency (no more Navigator.pushNamed)
- Fix goodbye view keyboard overflow (SingleChildScrollView)
- Add active session card on customer home screen with refresh on navigate back
- Fix PricingBottomSheet extension mode (RequestExtension instead of new pairing)
- Send session_resumed to both parties on extension accept

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client_app/lib/features/chat/widgets/pricing_bottom_sheet.dart

@@ -2,18 +2,45 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../../core/api/api_client.dart';
 import '../../../core/chat/chat_opening_bloc.dart';
+import '../../../core/chat/session_closure_bloc.dart';
 import '../../../core/pairing/pairing_bloc.dart';
 
 class PricingBottomSheet extends StatelessWidget {
-  const PricingBottomSheet({super.key});
+  /// If set, the bottom sheet is in "extension" mode — selecting a tier extends the session.
+  final String? extensionSessionId;
 
+  const PricingBottomSheet({super.key, this.extensionSessionId});
+
+  /// Show for new pairing (from home screen)
   static Future<void> show(BuildContext context) {
     return showModalBottomSheet(
       context: context,
       isScrollControlled: true,
       builder: (_) => BlocProvider(
         create: (ctx) => ChatOpeningBloc(apiClient: ctx.read<ApiClient>())..add(LoadPricing()),
-        child: const PricingBottomSheet(),
+        child: MultiBlocProvider(
+          providers: [
+            BlocProvider.value(value: context.read<PairingBloc>()),
+          ],
+          child: const PricingBottomSheet(),
+        ),
+      ),
+    );
+  }
+
+  /// Show for session extension (from chat screen)
+  static Future<void> showForExtension(BuildContext context, {required String sessionId}) {
+    return showModalBottomSheet(
+      context: context,
+      isScrollControlled: true,
+      builder: (_) => BlocProvider(
+        create: (ctx) => ChatOpeningBloc(apiClient: ctx.read<ApiClient>())..add(LoadPricing()),
+        child: MultiBlocProvider(
+          providers: [
+            BlocProvider.value(value: context.read<SessionClosureBloc>()),
+          ],
+          child: PricingBottomSheet(extensionSessionId: sessionId),
+        ),
       ),
     );
   }
@@ -30,6 +57,8 @@ class PricingBottomSheet extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final isExtension = extensionSessionId != null;
+
     return BlocBuilder<ChatOpeningBloc, ChatOpeningState>(
       builder: (context, state) {
         if (state is PricingLoading || state is PricingInitial) {
@@ -58,13 +87,13 @@ class PricingBottomSheet extends StatelessWidget {
                 child: ListView(
                   controller: scrollController,
                   children: [
-                    const Text(
-                      'Pilih Durasi Curhat',
-                      style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
+                    Text(
+                      isExtension ? 'Perpanjang Durasi' : 'Pilih Durasi Curhat',
+                      style: const TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
                       textAlign: TextAlign.center,
                     ),
                     const SizedBox(height: 16),
-                    if (state.freeTrialEligible) ...[
+                    if (!isExtension && state.freeTrialEligible) ...[
                       Card(
                         color: Colors.green.shade50,
                         child: ListTile(
@@ -89,11 +118,20 @@ class PricingBottomSheet extends StatelessWidget {
                         ),
                         onTap: () {
                           Navigator.of(context).pop();
-                          _startPairing(
-                            context,
-                            durationMinutes: tier.durationMinutes,
-                            price: tier.price,
-                          );
+                          if (isExtension) {
+                            _requestExtension(
+                              context,
+                              sessionId: extensionSessionId!,
+                              durationMinutes: tier.durationMinutes,
+                              price: tier.price,
+                            );
+                          } else {
+                            _startPairing(
+                              context,
+                              durationMinutes: tier.durationMinutes,
+                              price: tier.price,
+                            );
+                          }
                         },
                       ),
                     )),
@@ -116,4 +154,12 @@ class PricingBottomSheet extends StatelessWidget {
       isFreeTrial: isFreeTrial,
     ));
   }
+
+  void _requestExtension(BuildContext context, {required String sessionId, required int durationMinutes, required int price}) {
+    context.read<SessionClosureBloc>().add(RequestExtension(
+      sessionId: sessionId,
+      durationMinutes: durationMinutes,
+      price: price,
+    ));
+  }
 }