style: 全项目紫色→薄荷绿 Fresh Air 清新风

- 主色 #635BFF→#14B8A6 (薄荷绿)
- 浅紫 #EDEBFF→#E6FAF6 (极浅薄荷)
- 深紫 #4B44D6→#0F9D8E (深薄荷)
- 渐变紫→薄荷渐变
- 全局13种紫色映射替换

health_app/lib/pages/settings/settings_pages.dart

@@ -8,7 +8,7 @@ class SettingsPage extends ConsumerWidget {
 
   @override Widget build(BuildContext context, WidgetRef ref) {
     return Scaffold(
-      backgroundColor: const Color(0xFFF8F7FF),
+      backgroundColor: const Color(0xFFF6F9FB),
       appBar: AppBar(
         backgroundColor: Colors.white,
         elevation: 0,
@@ -72,7 +72,7 @@ class _SetItem extends StatelessWidget {
         padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 14),
         decoration: BoxDecoration(color: Colors.white),
         child: Row(children: [
-          Container(width: 36, height: 36, decoration: BoxDecoration(color: const Color(0xFFF5F3FF), borderRadius: BorderRadius.circular(10)), child: Icon(icon, size: 18, color: const Color(0xFF635BFF))),
+          Container(width: 36, height: 36, decoration: BoxDecoration(color: const Color(0xFFF2FAF9), borderRadius: BorderRadius.circular(10)), child: Icon(icon, size: 18, color: const Color(0xFF14B8A6))),
           const SizedBox(width: 12),
           Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [Text(title, style: const TextStyle(fontSize: 16, color: Color(0xFF1A1A1A))), if (subtitle != null && subtitle!.isNotEmpty) Text(subtitle!, style: TextStyle(fontSize: 13, color: Colors.grey[500]))])),
           if (trailingText != null && trailingText!.isNotEmpty) Text(trailingText!, style: TextStyle(fontSize: 14, color: Colors.grey[400])),