Phase 2 scaffold: mitra online status & pairing logic

Add mitra online/offline status with heartbeat-based auto-offline,
customer-mitra pairing via Valkey pub/sub blast, session management,
and control center dashboard with real-time stats.

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

mitra_app/lib/features/chat/screens/active_sessions_screen.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+import '../../../core/api/api_client.dart';
+
+class ActiveSessionsScreen extends StatefulWidget {
+  const ActiveSessionsScreen({super.key});
+
+  @override
+  State<ActiveSessionsScreen> createState() => _ActiveSessionsScreenState();
+}
+
+class _ActiveSessionsScreenState extends State<ActiveSessionsScreen> {
+  List<Map<String, dynamic>> _sessions = [];
+  bool _loading = true;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadSessions();
+  }
+
+  Future<void> _loadSessions() async {
+    try {
+      final apiClient = context.read<ApiClient>();
+      final response = await apiClient.get('/api/mitra/chat-requests/sessions/active');
+      setState(() {
+        _sessions = List<Map<String, dynamic>>.from(response['data'] as List);
+        _loading = false;
+      });
+    } catch (_) {
+      setState(() => _loading = false);
+    }
+  }
+
+  Future<void> _endSession(String sessionId) async {
+    final confirmed = await showDialog<bool>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: const Text('Akhiri Sesi?'),
+        content: const Text('Apakah kamu yakin ingin mengakhiri sesi ini?'),
+        actions: [
+          TextButton(onPressed: () => Navigator.of(ctx).pop(false), child: const Text('Batal')),
+          TextButton(onPressed: () => Navigator.of(ctx).pop(true), child: const Text('Ya, Akhiri')),
+        ],
+      ),
+    );
+
+    if (confirmed == true) {
+      try {
+        final apiClient = context.read<ApiClient>();
+        await apiClient.post('/api/mitra/chat-requests/sessions/$sessionId/end');
+        _loadSessions();
+      } catch (_) {
+        if (mounted) {
+          ScaffoldMessenger.of(context).showSnackBar(
+            const SnackBar(content: Text('Gagal mengakhiri sesi.')),
+          );
+        }
+      }
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Sesi Aktif')),
+      body: _loading
+          ? const Center(child: CircularProgressIndicator())
+          : _sessions.isEmpty
+              ? const Center(child: Text('Tidak ada sesi aktif.'))
+              : ListView.builder(
+                  itemCount: _sessions.length,
+                  itemBuilder: (context, index) {
+                    final session = _sessions[index];
+                    return ListTile(
+                      leading: const Icon(Icons.person),
+                      title: Text(session['customer_display_name'] as String? ?? 'Customer'),
+                      subtitle: Text('Status: ${session['status']}'),
+                      trailing: TextButton(
+                        onPressed: () => _endSession(session['id'] as String),
+                        child: const Text('Akhiri', style: TextStyle(color: Colors.red)),
+                      ),
+                    );
+                  },
+                ),
+    );
+  }
+}

mitra_app/lib/features/chat/widgets/incoming_request_sheet.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+import '../../../core/chat/chat_request_bloc.dart';
+
+class IncomingRequestSheet extends StatelessWidget {
+  final String sessionId;
+  const IncomingRequestSheet({super.key, required this.sessionId});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: const EdgeInsets.all(24),
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          const Icon(Icons.chat, size: 48, color: Colors.blue),
+          const SizedBox(height: 16),
+          const Text(
+            'Ada permintaan chat baru!',
+            style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
+          ),
+          const SizedBox(height: 8),
+          const Text(
+            'Seorang customer ingin curhat denganmu.',
+            style: TextStyle(fontSize: 14, color: Colors.grey),
+          ),
+          const SizedBox(height: 24),
+          Row(
+            children: [
+              Expanded(
+                child: OutlinedButton(
+                  onPressed: () {
+                    context.read<ChatRequestBloc>().add(DeclineRequest(sessionId));
+                    Navigator.of(context).pop();
+                  },
+                  child: const Text('Tolak'),
+                ),
+              ),
+              const SizedBox(width: 16),
+              Expanded(
+                child: ElevatedButton(
+                  onPressed: () {
+                    context.read<ChatRequestBloc>().add(AcceptRequest(sessionId));
+                    Navigator.of(context).pop();
+                  },
+                  child: const Text('Terima'),
+                ),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}