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/widgets/smart_select_card.dart

@@ -0,0 +1,82 @@
+// smart_select_card.dart — 节点页置顶「智能选择」推荐卡(纯展示)
+//
+// accent-subtle 底 + clay 渐变 zap 图标 + 「推荐」胶囊 + 脱敏文案,默认选中。
+import 'package:flutter/material.dart';
+
+import '../l10n/app_text.dart';
+import '../pangolin_theme.dart';
+import 'pangolin_icons.dart';
+
+class SmartSelectCard extends StatelessWidget {
+  const SmartSelectCard({super.key, required this.t, required this.selected, required this.onTap});
+
+  final AppText t;
+  final bool selected;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final c = context.pangolin;
+    return Material(
+      color: c.accentSubtle,
+      shape: RoundedRectangleBorder(
+        borderRadius: BorderRadius.circular(PangolinRadius.xl),
+        side: BorderSide(color: selected ? c.accent : c.accentBorder, width: 1.5),
+      ),
+      clipBehavior: Clip.antiAlias,
+      child: InkWell(
+        onTap: onTap,
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 15),
+          child: Row(
+            children: [
+              Container(
+                width: 42,
+                height: 42,
+                decoration: BoxDecoration(
+                  gradient: const LinearGradient(
+                    begin: Alignment.topLeft,
+                    end: Alignment.bottomRight,
+                    colors: [PangolinColors.clay500, PangolinColors.clay700],
+                  ),
+                  borderRadius: BorderRadius.circular(PangolinRadius.md),
+                ),
+                child: const Icon(PangolinIcons.zap, size: 21, color: PangolinColors.white),
+              ),
+              const SizedBox(width: 13),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Row(children: [
+                      Flexible(
+                        child: Text(t.smartSelect,
+                            style: PangolinText.body
+                                .copyWith(color: c.fg1, fontWeight: FontWeight.w700, fontSize: 15.5)),
+                      ),
+                      const SizedBox(width: 8),
+                      Container(
+                        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 2),
+                        decoration: BoxDecoration(color: c.accent, borderRadius: BorderRadius.circular(PangolinRadius.full)),
+                        child: Text(t.recommended,
+                            style: PangolinText.caption.copyWith(
+                                color: c.fgOnAccent, fontWeight: FontWeight.w700, fontSize: 10)),
+                      ),
+                    ]),
+                    const SizedBox(height: 3),
+                    Text(t.smartSub,
+                        style: PangolinText.caption.copyWith(color: c.fg2, fontWeight: FontWeight.w400, height: 1.5)),
+                  ],
+                ),
+              ),
+              if (selected) ...[
+                const SizedBox(width: 8),
+                Icon(PangolinIcons.check, size: 19, color: c.accent),
+              ],
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}