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/widgets/agent_bar.dart

@@ -43,16 +43,16 @@ class AgentBar extends ConsumerWidget {
         margin: const EdgeInsets.symmetric(horizontal: 4, vertical: 6),
         padding: const EdgeInsets.symmetric(horizontal: 14),
         decoration: BoxDecoration(
-          color: isSelected ? const Color(0xFF635BFF) : Colors.white,
-          border: Border.all(color: const Color(0xFF635BFF)),
+          color: isSelected ? const Color(0xFF14B8A6) : Colors.white,
+          border: Border.all(color: const Color(0xFF14B8A6)),
           borderRadius: BorderRadius.circular(24),
         ),
         child: Row(
           mainAxisSize: MainAxisSize.min,
           children: [
-            Icon(icon, size: 16, color: isSelected ? Colors.white : const Color(0xFF635BFF)),
+            Icon(icon, size: 16, color: isSelected ? Colors.white : const Color(0xFF14B8A6)),
             const SizedBox(width: 6),
-            Text(label, style: TextStyle(fontSize: 13, color: isSelected ? Colors.white : const Color(0xFF635BFF))),
+            Text(label, style: TextStyle(fontSize: 13, color: isSelected ? Colors.white : const Color(0xFF14B8A6))),
           ],
         ),
       ),