feat(client): 全模块 API 对接 + 修复登陆跳转 + 菜单 UI 优化

API 对接：
- 入库/出库/库存/财务/往来单位/基础数据全部对接后端 REST API
- 新增 repositories、providers、models 层，统一分层架构
- auth 从 flutter_secure_storage 迁移到 shared_preferences

登陆跳转修复：
- 将 _RouterNotifier 提取为独立 Riverpod provider，appRouterProvider
  使用 ref.read 避免依赖链导致 router 重建后跳回 /login
- redirect 函数新增 initialized 守卫，防止 auth 未恢复时误重定向
- 添加调试日志（Router/Auth/ApiClient）定位 401 触发的 logout 链路

退出菜单 UI：
- 去掉 ListTile，改用 Row + 自定义 padding，文字左对齐
- MouseRegion + AnimatedContainer 实现 hover 高亮（普通项蓝底/退出红底）
- 菜单圆角 6px，elevation 8，分割线高度 1px

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

client/lib/providers/partner_provider.dart

@@ -0,0 +1,78 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../core/api/api_client.dart';
+import '../core/auth/auth_state.dart';
+import '../core/models/page_result.dart';
+import '../models/partner.dart';
+import '../repositories/partner_repository.dart';
+
+final partnerRepositoryProvider = Provider<PartnerRepository>((ref) {
+  return PartnerRepository(ref.watch(apiClientProvider));
+});
+
+// Supplier list provider for dropdowns
+final supplierListProvider =
+    AsyncNotifierProvider<PartnerListNotifier, PageResult<Partner>>(
+  () => PartnerListNotifier(type: 'supplier'),
+);
+
+// Customer list provider
+final customerListProvider =
+    AsyncNotifierProvider<PartnerListNotifier, PageResult<Partner>>(
+  () => PartnerListNotifier(type: 'customer'),
+);
+
+class PartnerListNotifier extends AsyncNotifier<PageResult<Partner>> {
+  final String? type;
+  int _page = 1;
+  String _keyword = '';
+
+  PartnerListNotifier({this.type});
+
+  @override
+  Future<PageResult<Partner>> build() {
+    ref.watch(authStateProvider.select((s) => s.user?.shopId));
+    return _fetch();
+  }
+
+  Future<PageResult<Partner>> _fetch() {
+    return ref.read(partnerRepositoryProvider).list(
+          type: type,
+          keyword: _keyword.isEmpty ? null : _keyword,
+          page: _page,
+        );
+  }
+
+  void setPage(int page) {
+    _page = page;
+    reload();
+  }
+
+  void setKeyword(String keyword) {
+    _keyword = keyword;
+    _page = 1;
+    reload();
+  }
+
+  void reload() {
+    state = const AsyncValue.loading();
+    _fetch().then(
+      (result) => state = AsyncValue.data(result),
+      onError: (e, st) => state = AsyncValue.error(e, st),
+    );
+  }
+
+  Future<void> createPartner(Map<String, dynamic> data) async {
+    await ref.read(partnerRepositoryProvider).create(data);
+    reload();
+  }
+
+  Future<void> updatePartner(int id, Map<String, dynamic> data) async {
+    await ref.read(partnerRepositoryProvider).update(id, data);
+    reload();
+  }
+
+  Future<void> deletePartner(int id) async {
+    await ref.read(partnerRepositoryProvider).delete(id);
+    reload();
+  }
+}