feat(client): Flutter 逐屏还原 + iPad ≥900 断点 (tsk_gpPXi-icyeOE)

对照 design/ui_kits mobile+tablet 原型逐屏补齐 Flutter 客户端:

- l10n 资源层(strings_zh/en,单显)+ Riverpod 状态层(连接状态机/免费额度/
  节点选择/语言/主题),UI 与数据解耦,mock 数据接 API 不动 UI。
- 连接键严格三态(off 虚线轨道环 / connecting 旋转弧 / on 满环+计时+光晕),
  状态来自 connectionProvider,点击只派发事件——禁止乐观显示。
- 节点页置顶「智能选择」推荐卡(clay 渐变 zap + 推荐胶囊,默认选中);
  免费额度卡(剩余分钟+进度条 ≤3 分钟切 warning + 看广告解锁变绿)。
- Tab 左右滑动切换(手势竞技场仲裁,子页滚动不误触发,200ms 方向感知滑入)。
- iPad/宽屏 ≥900 LayoutBuilder 切侧栏分栏(导航行高 ≥48,连接页双栏/节点双列网格),
  复用同一批原子组件,不 fork 页面。
- 语义 token 零硬编码;文案全部走 l10n;套餐数字对齐 §7;无支付表单/emoji 国旗。
- CI 红线词扫描扩展到 client/lib;新增 Flutter analyze+test CI 任务。
- 测试:连接状态机/额度/节点单测、连接键三态与卡片组件测试、
  golden(连接键三态/推荐卡/额度卡 × 明暗)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/main.dart

@@ -1,30 +1,29 @@
 // main.dart — 入口(演示态)
-// 串接:登录 → 引导 → 主框架(4 Tab)
+// 串接:登录 → 引导 → 主框架(4 Tab);状态层统一走 Riverpod。
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
 import 'pangolin_theme.dart';
-import 'widgets/pangolin_widgets.dart';
+import 'state/app_providers.dart';
+import 'widgets/auth_screen.dart';
+import 'widgets/home_shell.dart';
+import 'widgets/onboarding_screen.dart';
 
-void main() => runApp(const PangolinApp());
+void main() => runApp(const ProviderScope(child: PangolinApp()));
 
-class PangolinApp extends StatefulWidget {
+class PangolinApp extends ConsumerWidget {
   const PangolinApp({super.key});
-  @override
-  State<PangolinApp> createState() => _PangolinAppState();
-}
-
-class _PangolinAppState extends State<PangolinApp> {
-  bool zh = true;
-  ThemeMode mode = ThemeMode.system;
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
+    final mode = ref.watch(themeModeProvider);
     return MaterialApp(
       title: '穿山甲',
       debugShowCheckedModeBanner: false,
       theme: PangolinTheme.light,
       darkTheme: PangolinTheme.dark,
       themeMode: mode,
-      home: RootFlow(zh: zh),
+      home: const RootFlow(),
     );
   }
 }
@@ -32,25 +31,25 @@ class _PangolinAppState extends State<PangolinApp> {
 /// 应用阶段:登录 → 引导 → 主应用
 enum AppStage { auth, onboarding, app }
 
-class RootFlow extends StatefulWidget {
-  const RootFlow({super.key, this.zh = true});
-  final bool zh;
+class RootFlow extends ConsumerStatefulWidget {
+  const RootFlow({super.key});
   @override
-  State<RootFlow> createState() => _RootFlowState();
+  ConsumerState<RootFlow> createState() => _RootFlowState();
 }
 
-class _RootFlowState extends State<RootFlow> {
+class _RootFlowState extends ConsumerState<RootFlow> {
   AppStage stage = AppStage.auth;
 
   @override
   Widget build(BuildContext context) {
+    final t = ref.watch(appTextProvider);
     switch (stage) {
       case AppStage.auth:
-        return AuthScreen(zh: widget.zh, onDone: () => setState(() => stage = AppStage.onboarding));
+        return AuthScreen(t: t, onDone: () => setState(() => stage = AppStage.onboarding));
       case AppStage.onboarding:
-        return OnboardingScreen(onDone: () => setState(() => stage = AppStage.app));
+        return OnboardingScreen(t: t, onDone: () => setState(() => stage = AppStage.app));
       case AppStage.app:
-        return HomeShell(zh: widget.zh);
+        return const HomeShell();
     }
   }
 }