feat: Cupertino滚轮选择器 + 品牌更名 + UI全面优化

- 日期/时间/次数选择器统一改为底部弹出Cupertino滚轮，无单位标签，双横线选区
- App更名为"小脉健康"，副标题"血管病患者的AI健康管理助手"
- 健康仪表盘及侧边栏移除体重指标，侧边栏背景改为蓝白渐变
- 健康档案按钮移入功能入口网格，与其他入口样式统一
- 记数据智能体配色改为绿色渐变(#A1FFCE→#69DB8F)
- 隐私协议/关于页从Text改为MarkdownBody正确渲染
- 运动计划/饮食记录卡片添加边框和阴影
- 服药次数从chip改为滚轮选择器
- 日期显示格式统一为空格分隔(1999 01 01)
- 健康档案页背景改为纯白

health_app/lib/pages/home/home_page.dart

@@ -155,7 +155,7 @@ class _HomePageState extends ConsumerState<HomePage> {
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
                 const Text(
-                  'AI 健康管家',
+                  '小脉健康',
                   style: TextStyle(
                     fontSize: 12,
                     fontWeight: FontWeight.w600,
@@ -269,7 +269,7 @@ class _HomePageState extends ConsumerState<HomePage> {
       ActiveAgent.health => const LinearGradient(
         begin: Alignment.topCenter,
         end: Alignment.bottomCenter,
-        colors: [Color(0xFFFFAFBD), Color(0xFFC9FFBF)],
+        colors: [Color(0xFFA1FFCE), Color(0xFF69DB8F)],
       ),
       ActiveAgent.diet => const LinearGradient(
         begin: Alignment.topCenter,

health_app/lib/pages/home/widgets/chat_messages_view.dart

@@ -89,7 +89,7 @@ class ChatMessagesView extends ConsumerWidget {
             ),
             const SizedBox(height: 16),
             Text(
-              '开始和 AI 健康管家对话吧',
+              '开始和小脉健康对话吧',
               style: Theme.of(context).textTheme.bodyMedium,
             ),
             const SizedBox(height: 8),
@@ -1181,7 +1181,7 @@ class ChatMessagesView extends ConsumerWidget {
                     ),
                     const SizedBox(width: 6),
                     const Text(
-                      '健康管家',
+                      '小脉健康',
                       style: TextStyle(fontSize: 15, color: AppColors.textHint),
                     ),
                     const SizedBox(width: 4),
@@ -1343,11 +1343,11 @@ class ChatMessagesView extends ConsumerWidget {
         verticalGradient: true,
       ),
       ActiveAgent.health => _AgentColors(
-        gradient: [Color(0xFFFFAFBD), Color(0xFFC9FFBF)],
-        bg: const Color(0xFFF7FDEB),
-        border: const Color(0xFFEAF7BF),
-        iconBg: const Color(0xFFF9FCEB),
-        accent: const Color(0xFF8BD982),
+        gradient: [Color(0xFFA1FFCE), Color(0xFF69DB8F)],
+        bg: const Color(0xFFF4FEF2),
+        border: const Color(0xFFD4F0C8),
+        iconBg: const Color(0xFFF0FCEF),
+        accent: const Color(0xFF52B87A),
         verticalGradient: true,
       ),
       ActiveAgent.diet => _AgentColors(
@@ -1404,7 +1404,7 @@ class ChatMessagesView extends ConsumerWidget {
       ),
       ActiveAgent.report => (LucideIcons.fileText, '报告分析', '上传体检报告，AI 辅助解读'),
       ActiveAgent.exercise => (LucideIcons.activity, '运动', '制定运动计划，打卡记录进度'),
-      _ => (Icons.forum_outlined, 'AI 助手', '您的智能健康管家'),
+      _ => (Icons.forum_outlined, 'AI 助手', '血管病患者的 AI 健康管理助手'),
     };
   }
 
@@ -1692,7 +1692,6 @@ class ChatMessagesView extends ConsumerWidget {
       decoration: BoxDecoration(
         color: Colors.white,
         borderRadius: BorderRadius.circular(28),
-        border: Border.all(color: Color(0xFFE2E8F0), width: 2),
         boxShadow: AppColors.cardShadow,
       ),
       clipBehavior: Clip.antiAlias,