feat: 新增站内消息系统，支持通知与订单跳转

lib/features/notice/application/notice_alert_controller.dart

@@ -0,0 +1,86 @@
+import 'dart:async';
+
+import 'package:flutter/widgets.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../../core/network/api_response.dart';
+import '../../../core/notifications/local_notifications.dart';
+import '../../../core/providers.dart';
+import '../../auth/application/session_controller.dart';
+import 'notice_routes.dart';
+
+/// 轮询未读站内消息，并在 App 不处于前台时弹出系统通知。
+///
+/// 登录后每 30s 拉一次未读列表；已提醒过的最大消息 id 持久化，
+/// 重启后不会重复提醒历史消息。
+final noticeAlertProvider =
+    NotifierProvider<NoticeAlertController, int>(NoticeAlertController.new);
+
+class NoticeAlertController extends Notifier<int> {
+  static const _interval = Duration(seconds: 30);
+
+  Timer? _timer;
+  bool _busy = false;
+
+  @override
+  int build() {
+    _timer?.cancel();
+    _timer = null;
+
+    final loggedIn = ref.watch(sessionProvider.select((s) => s.isLoggedIn));
+    if (!loggedIn) return 0;
+
+    ref.onDispose(() {
+      _timer?.cancel();
+      _timer = null;
+    });
+    _timer = Timer.periodic(_interval, (_) => unawaited(_poll()));
+    unawaited(_poll());
+    return 0;
+  }
+
+  Future<void> _poll() async {
+    if (_busy) return;
+    _busy = true;
+    try {
+      final res = await ref
+          .read(noticeApiProvider)
+          .list(pageSize: 20, isRead: false);
+      if (!res.isOk || res.data == null || res.data!.list.isEmpty) return;
+
+      final notices = res.data!.list;
+      final latest = notices.fold<int>(0, (m, n) => n.id > m ? n.id : m);
+      final storage = ref.read(tokenStorageProvider);
+
+      // 首次运行只记录基线，避免把历史未读一次性弹成通知
+      final maxId = storage.noticeAlertMaxId;
+      if (maxId < 0) {
+        await storage.setNoticeAlertMaxId(latest);
+        return;
+      }
+
+      final fresh = notices.where((n) => n.id > maxId).toList()
+        ..sort((a, b) => a.id.compareTo(b.id));
+      if (fresh.isEmpty) return;
+
+      // 前台时只更新基线（界面内已有红点/消息中心），退到后台才弹通知
+      final inBackground =
+          WidgetsBinding.instance.lifecycleState != AppLifecycleState.resumed;
+      if (inBackground) {
+        for (final notice in fresh) {
+          await LocalNotifications.instance.show(
+            id: notice.id,
+            title: notice.title,
+            body: notice.content,
+            route: noticeRoute(notice) ?? '/notice',
+          );
+        }
+      }
+      await storage.setNoticeAlertMaxId(latest);
+    } on ApiException {
+      // 网络波动忽略，下一轮再试
+    } finally {
+      _busy = false;
+    }
+  }
+}

lib/features/notice/application/notice_routes.dart

@@ -0,0 +1,18 @@
+import '../data/notice_api.dart';
+
+/// 消息可跳转的订单路由；无法识别业务类型时返回 null。
+///
+/// 与后端通知投递的 `bizType` 约定一致：
+/// `survey_order` / `repair_dispatch` / `install_order` / `maintenance_order`。
+String? noticeRoute(Notice notice) {
+  final id = notice.bizId;
+  if (id == null || id <= 0) return null;
+  final source = switch (notice.bizType) {
+    'survey_order' => 'survey',
+    'repair_dispatch' || 'repair_order' => 'repair',
+    'install_order' => 'install',
+    'maintenance_order' => 'maintenance',
+    _ => null,
+  };
+  return source == null ? null : '/order/$source/$id';
+}