feat(client): 网络恢复自动刷新 + 离线嗅探 + 连通性感知登录

网络嗅探与自动恢复：
- ConnectivityNotifier：在线时 30s 检测，离线时切换为 1min 嗅探
- 新增 networkRecoveryCountProvider：网络恢复时自增，各数据 provider
  通过 ref.watch 实现自动重新加载
- inventory/product/stock_in/stock_out/partner provider 均已接入

FutureBuilder 类屏幕：
- finance_screen + batch_tracking_screen 通过 ref.listen 监听恢复事件

修复问题 1：API 超时 10s/30s → 5s/15s，减少无网络时等待
修复问题 2：offline banner 文字由"写操作已禁用"改为实际行为描述

连通性感知：
- app 启动时（_AppBootstrap）立即 forceCheck，路由跳转前状态已就绪
- 登录页：watch connectivityProvider，离线时显示警告 banner
- 登录按钮：离线状态下直接提示，不等待超时

测试：
- login_screen_test + login_flow_test 通过 ConnectivityNotifier(skipInit: true)
  覆盖 provider，避免测试环境中 pending HTTP timer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/providers/connectivity_provider.dart

@@ -3,34 +3,67 @@ import 'package:dio/dio.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../core/config/app_config.dart';
 
+/// 每次从离线恢复到在线时自增。
+/// 数据 provider 通过 watch 此值实现网络恢复后自动刷新。
+final networkRecoveryCountProvider = StateProvider<int>((ref) => 0);
+
 final connectivityProvider =
     StateNotifierProvider<ConnectivityNotifier, bool>((ref) {
-  return ConnectivityNotifier();
+  return ConnectivityNotifier(
+    onRecovered: () {
+      ref.read(networkRecoveryCountProvider.notifier).update((s) => s + 1);
+    },
+  );
 });
 
 class ConnectivityNotifier extends StateNotifier<bool> {
-  ConnectivityNotifier() : super(true) {
-    _check(); // immediate first check
-    _timer = Timer.periodic(const Duration(seconds: 30), (_) => _check());
+  final void Function()? onRecovered;
+
+  ConnectivityNotifier({this.onRecovered, bool skipInit = false}) : super(true) {
+    if (!skipInit) {
+      _check();
+      _startOnlineTimer();
+    }
   }
 
   Timer? _timer;
 
-  // Dedicated lightweight Dio — short timeouts, no interceptors
+  // 独立轻量 Dio：短超时，无拦截器
   final _dio = Dio(BaseOptions(
     connectTimeout: const Duration(seconds: 3),
     receiveTimeout: const Duration(seconds: 3),
   ));
 
-  /// 立即触发一次检测（供外部调用，如 API 请求失败时）
+  /// 在线时：每 30 秒检测一次
+  void _startOnlineTimer() {
+    _timer?.cancel();
+    _timer = Timer.periodic(const Duration(seconds: 30), (_) => _check());
+  }
+
+  /// 离线时：每 1 分钟嗅探一次，降低频率节省资源
+  void _startOfflineTimer() {
+    _timer?.cancel();
+    _timer = Timer.periodic(const Duration(minutes: 1), (_) => _check());
+  }
+
+  /// 立即触发一次检测（供外部调用，如 API 请求失败 / 启动时）
   Future<void> forceCheck() => _check();
 
   Future<void> _check() async {
     try {
       await _dio.get(AppConfig.healthUrl);
-      if (!state) state = true;
+      if (!state) {
+        // 离线 → 在线：切回高频检测，广播恢复事件
+        state = true;
+        onRecovered?.call();
+        _startOnlineTimer();
+      }
     } catch (_) {
-      if (state) state = false;
+      if (state) {
+        // 在线 → 离线：切换为低频嗅探
+        state = false;
+        _startOfflineTimer();
+      }
     }
   }
 

client/lib/providers/inventory_provider.dart

@@ -4,6 +4,7 @@ import '../core/auth/auth_state.dart';
 import '../core/models/page_result.dart';
 import '../models/inventory.dart';
 import '../repositories/inventory_repository.dart';
+import 'connectivity_provider.dart';
 
 final inventoryRepositoryProvider = Provider<InventoryRepository>((ref) {
   return InventoryRepository(ref.watch(apiClientProvider));
@@ -23,6 +24,7 @@ class InventoryListNotifier extends AsyncNotifier<PageResult<Inventory>> {
   @override
   Future<PageResult<Inventory>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider); // 网络恢复时自动刷新
     try {
       final result = await _fetch();
       _cache = result;
@@ -86,6 +88,7 @@ class InventoryLogNotifier extends AsyncNotifier<PageResult<InventoryLog>> {
   @override
   Future<PageResult<InventoryLog>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider);
     try {
       final result = await _fetch();
       _cache = result;

client/lib/providers/partner_provider.dart

@@ -4,6 +4,7 @@ import '../core/auth/auth_state.dart';
 import '../core/models/page_result.dart';
 import '../models/partner.dart';
 import '../repositories/partner_repository.dart';
+import 'connectivity_provider.dart';
 
 final partnerRepositoryProvider = Provider<PartnerRepository>((ref) {
   return PartnerRepository(ref.watch(apiClientProvider));
@@ -32,6 +33,7 @@ class PartnerListNotifier extends AsyncNotifier<PageResult<Partner>> {
   @override
   Future<PageResult<Partner>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider);
     try {
       final result = await _fetch();
       _cache = result;

client/lib/providers/product_provider.dart

@@ -4,6 +4,7 @@ import '../core/auth/auth_state.dart';
 import '../core/models/page_result.dart';
 import '../models/product.dart';
 import '../repositories/product_repository.dart';
+import 'connectivity_provider.dart';
 
 final productRepositoryProvider = Provider<ProductRepository>((ref) {
   return ProductRepository(ref.watch(apiClientProvider));
@@ -23,6 +24,7 @@ class ProductListNotifier extends AsyncNotifier<PageResult<Product>> {
   @override
   Future<PageResult<Product>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider);
     try {
       final result = await _fetch();
       _cache = result;

client/lib/providers/stock_in_provider.dart

@@ -4,6 +4,7 @@ import '../core/auth/auth_state.dart';
 import '../core/models/page_result.dart';
 import '../models/stock_in.dart';
 import '../repositories/stock_in_repository.dart';
+import 'connectivity_provider.dart';
 import 'inventory_provider.dart';
 
 final stockInRepositoryProvider = Provider<StockInRepository>((ref) {
@@ -25,6 +26,7 @@ class StockInListNotifier extends AsyncNotifier<PageResult<StockInOrder>> {
   @override
   Future<PageResult<StockInOrder>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider);
     try {
       final result = await _fetch();
       _cache = result;

client/lib/providers/stock_out_provider.dart

@@ -4,6 +4,7 @@ import '../core/auth/auth_state.dart';
 import '../core/models/page_result.dart';
 import '../models/stock_out.dart';
 import '../repositories/stock_out_repository.dart';
+import 'connectivity_provider.dart';
 import 'inventory_provider.dart';
 
 final stockOutRepositoryProvider = Provider<StockOutRepository>((ref) {
@@ -25,6 +26,7 @@ class StockOutListNotifier extends AsyncNotifier<PageResult<StockOutOrder>> {
   @override
   Future<PageResult<StockOutOrder>> build() async {
     ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    ref.watch(networkRecoveryCountProvider);
     try {
       final result = await _fetch();
       _cache = result;