feat: UI 系统中心化 + 趋势图重构 + 法律文档 H5 上线

- UI 系统: 新增 design_tokens / module_visuals / app_buttons / app_status_badge / app_toast / ai_content 六个共享模块; 28 个页面接入, SnackBar 全部替换为 AppToast
- 趋势图: 直线折线 + 渐变填充 + 阴影; 去网格线; X 轴日+月份分隔; Y 轴整数刻度最多 4 个; 点击数据点/录入记录显示上方浮层, 选中点变实心
- 法律文档 H5: 后端 wwwroot 托管隐私政策/服务协议/关于/个人信息收集清单/第三方 SDK 清单 + 索引页; Program.cs 启用 UseDefaultFiles + UseStaticFiles
- 其他: auth_provider 登录流程调整; api_client IP 适配; 主页智能体栏间距优化

health_app/lib/widgets/app_status_badge.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/material.dart';
+
+import '../core/app_colors.dart';
+import '../core/app_design_tokens.dart';
+
+class AppStatusBadge extends StatelessWidget {
+  final String label;
+  final Color color;
+  final Color? backgroundColor;
+  final IconData? icon;
+
+  const AppStatusBadge({
+    super.key,
+    required this.label,
+    required this.color,
+    this.backgroundColor,
+    this.icon,
+  });
+
+  @override
+  Widget build(BuildContext context) => Container(
+    constraints: const BoxConstraints(minHeight: 24),
+    padding: const EdgeInsets.symmetric(horizontal: 9, vertical: 4),
+    decoration: BoxDecoration(
+      color: backgroundColor ?? color.withValues(alpha: 0.10),
+      borderRadius: AppRadius.pillBorder,
+      border: Border.all(color: color.withValues(alpha: 0.18)),
+    ),
+    child: Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        if (icon != null) ...[
+          Icon(icon, size: 14, color: color),
+          const SizedBox(width: 4),
+        ],
+        Text(label, style: AppTextStyles.tag.copyWith(color: color)),
+      ],
+    ),
+  );
+}
+
+class AppStatusColors {
+  AppStatusColors._();
+
+  static Color done = AppColors.success;
+  static Color warning = AppColors.warning;
+  static Color danger = AppColors.error;
+  static Color info = AppColors.health;
+}
+